Category Archives: Toxins Contaminants

Phosphate Removers Are A Waste of Money

You should be aware that in the normal scheme of things, phosphates cause algae to flourish. As such, phosphates became ‘the enemy’ to marketing weasels who would have you believe that algae are the bane of our existence. Phosphates are not considered overtly harmful to fish in naturally occurring amounts. Phosphate removers will attempt to remove phosphates from the water, but you should know that the products are just an exhaustible resin.  Once they have accomplished their goal, and your water is blissfully free of phosphates, you will probably have poor-doing plants because plants tend to require Phosphates, Nitrate and iron to flourish. You will probably have higher than ideal Nitrate levels because they are not being used efficiently by plants. Worse; the fish will soon be fed, and then have a bowel movement, which completely replaces your preciously reduced phosphates. It’s a losing battle. When the phosphate removing resin is completely exhausted, you can replace it and start over again.

Water Changes for Health, and Ammonia Control

If fish are suffering illness due to any obvious deterioration of water quality, you are well advised to begin a systematic daily changing of 20-40% of the total volume in the system.

There are some important points to consider before going out and wholesale changing the water.

First, make sure the water change does not radically change the temperature of the system.

Secondly, be sure that the water change does not result in truly electrolyte poor water. One test of this is the Total Alkalinity, but other salts are important as well. It might no hurt to add a teaspoon of salt per gallon of water in any major water change where live plants are not being maintained. This will ease the stress of the change on the fish and stimulate the production of a healthy, protective slime coating.
Scaleless fishes will not be harmed by that salt dose, the salt to use would be either non iodized table salt or sea salts.

The final consideration in doing daily, massive water changes, is to be sure the pH is not fluctuating wildly with each change. Does the tap water resemble the pH in the system?

Water Changes for Health, and Ammonia Control
Water Changes for Health, and Ammonia Control

As a side note, be careful about adding all sorts of fancy water conditioners to the water. For example, the product that rhymes with Press Coat is a synthetic agent that coats the fish with a protective coating. Neat. But consider that until it is reformulated, it will be a detriment because the gills are coated as well. This can complicate respiration where the gills were not functioning beautifully to begin with.

Another set of chemicals are sold to bind Ammonia. They use aldehydes to accomplish this feat. The aldehydes can accumulate and become caustic to fish if no ammonias are actually present. They are useful, but should be used sparingly and judiciously.

So, to re-cap, change 20-40% per day, watching temp and supporting Total Alkalinity and electrolytes. Consider adding a teaspoon of salt per gallon with the changes, and finally, don’t go overboard on the water conditioners.

On the long term, Constant Inflow Water Changes are a good idea. Installing a “drip irrigation system” TO a pond or tank brings SLOW inflow of new water, and a simple overflow device (overflow box) lets water leave the system. Ideally, you would replace 10-20% of the system volume per week. This is a VERY low flow taken on the 24hr x 7d cycle. No dechlorinator is needed.

The pundits will attack the assertion that ‘no dechlorinator is needed for drip irrigation water changes’ BEFORE they do any math on just how much “New” chlorinated water is in the system at any given time. (Drip Irrigation Water Changes)

Dr ErikJohnson

Hydrogen Sulfide Pond Gas – Not Very Common

Hydrogen Sulfide gas is a gas produced in an-aerobic pockets under water. These may occur anywhere there is deep sand or sediment, or in a sump with thick mulm.

Hydrogen Sulfide Pond Gas – Not Very Common

Without Oxygen, some bacteria can respire by using Sufur, and this creates Hydrogen Sulfide, H2S which is very, very toxic to fish.
HACH Chemical has a test for this,

Hach Company
P.O. Box 389
Loveland, Colorado
Phone: 800-227-4224
Fax: 970-669-2932

…but H2S intoxication should be suspected in any case of fish loss where:
1) There are no parasites, proven by microscopy,
2) There are no real Ammonia or Nitrite derangements
3) The signs are respiratory and
4)The history has some reference to a stalled filter or the stirring of stagnant gravel or media.
5) NEUROLOGICAL signs, of spinning, flipping and fearlessness may be seen just before death occurs.

The smell is one of rotting eggs. Losses may be great and they will continue after the H2S is long gone. If you discover or suspect H2S poisoning, you should REMOVE THE FISH before disturbing ANY gravel or sand.

Hydrogen Sulfide Pond Gas - Not Very Common
Hydrogen Sulfide Pond Gas – Not Very Common

Also, to neutralize SOME of the hydrogen sulfide, a weak dose of Potassium permanganate may be effective. Still, housekeeping, and finding the source of the anaerobic bacteria is the priority.

I’ve heard from a LOT of people that Aquascape ponds have Hydrogen Sulfide problems. I have tested dozens of these, especially the older ones since they are the most lored to have a problem – and have found NO H2S. My kit is the pad test from Hach. H2S is not an issue of pond TYPE but purely of pond maintenance.

Tannin Stains or Yellow Water and It’s Treatment

My pond is about 3 months old. The water is clear but has a yellowish tint that I would like to get rid of. I have koi and water plants in the pond. All my water tests are fine except the water seems to be ‘hard’ and the pH is about 8.5 in the afternoon. What could be causing the yellowish tint and what product do you have to correct it?

There are at least three places “yellowing” can come from and they are NEVER good for fish.

Tannin Stains or Yellow Water and It’s Treatment

If Ammonia accumulates sufficiently, it can cause a yellow cast to the water. Of course, this is easily tested – and not the most common cause of water-yellowing.

Leaves which fall into the pond will decay and cause yellowing. This is the release of tannins – which are astringent for fish. They are NOT terminal, or deadly, but they represent deterioration of water quality which especially makes fish more vulnerable to disease organisms.

Tannin Stains or Yellow Water and It's Treatment
Tannin Stains or Yellow Water and It’s Treatment

The most common cause of yellowish casting of the water is plants and their pots, or bog gardens which share water with the main pond. This is the most common and the worst cause of yellowing in the water. Basically it’s a “tea” being made with your pondwater percolating in and around the dirty root ball of the plants. Soil tea. The tannins (and humic acid) leeching from the soil in a bog will control green water. It will also decrease the pH in the system. Sometimes that’s a bad thing, sometimes it’s good.

It’s important NOT to let bogs stagnate. In some bog gardens, there are numerous decay processes which liberate noxious gases, carbon dioxide, and which consume dissolved oxygen. Stagnant bogs also contribute unnecessarily to the elevation of dissolved organics – background pollution. In other words – stagnant bogs are bad. Keep the water moving through the bogs. It’s better for the plants and it contributes to nitrate reduction. The roots of many bog plants contribute plant agglutinins to the water which makes it healthier and drops virus and bacterial counts.

Note: 2008 Spring –  All ponds need water changes. The more fish and fish wastes, and sometimes, the better the filtration – the more important water changes become. I’ve been using 1/8th inch ID irrigation line to supply my various ponds and tanks with constant inflow of fresh water as a form of 10% per week all the time water change. I’ve written that up on this web site.
Anyway; not all bogs are bad. Some are crafted from gravel with an intentional and uniform “upflow” or “downflow” limnion and are well engineered for filtration. These gravel bogs may have abundant plant material PLANTED IN THE GRAVEL – not in root balls. I have several of these set up and I am ENTHRALLED with their performance.

Potted plants can leach tannins and other amber colored contaminants from their soil into the pond. These are almost as hazardous as bog effluents. Folks are highly recommended to repot their plants in large sized aggregate gravel, and replant the plants every year to minimize the development of anaerobic decay conditions in the pots.

Please do not allow your water to become or remain yellow.

Water testing can rule out Ammonia’s contribution to yellow stained water.

If Tannins are incriminated, remove all leaf litter and take your bog gardens off line or improve the bogs’ through flows and eliminate stagnation – leaving the pond to have it’s own clear clean well oxygenated water.

Finally, a major water change will remove most of the yellow color.

If major water changes are not feasible, then you can use carbon to control the yellow color. Carbon is a black aggregate media which is made from superheating organic materials like coconut shell and wood as if in a kiln, except in the absence of oxygen. The product is black and light in weight.

After rinsing, the carbon can be put in a nylon mesh bag and placed directly in the water flow. It is NOT as effective to put the carbon in your waterfall because even though the water is moving rapidly, it’s not moving THROUGH the carbon bag. This takes some engineering. If you can get ALL your water through a pump in three hours, and that pump goes through a five gallon bucket half-full of carbon in mesh bags without channeling or bypass, you will see gin-clear water in two days. The idea is that ALL the water is PUSHED THROUGH the carbon. Not just over it.

Carbon expires rapidly, in direct proportion to the organics in the system. If the system has a lot of tannins – the carbon will expire on the order of days. After replacement, with cleaner water the next bags of carbon will last longer.

Unsure if the carbon still works? Simply take some and put it in a glass of water. Add a couple drops of Methylene Blue. Check it again in the morning. If the MB is gone, the carbon still has some “life” in it.

Using Rotenone To Renovate Fish Populations In Farm Ponds

Written by Dr. Martin Brunson

Rotenone – To Kill 100% of Fish Population – by Dr. Martin Brunson

Using Rotenone To Renovate Fish Populations In Farm Ponds

The ultimate fate of many farm ponds in Mississippi is an unbalanced fish population that is undesirable to fishermen, and, therefore, has little recreational fishing value. Once a fish population reaches such a condition, the best alternative is usually to eliminate the resident fish completely and to restock with a desirable combination of fish at recommended rates. Consult a fisheries biologist to determine the condition of your pond and the possible need for a complete fish population renovation.

Using Rotenone To Renovate Fish Populations In Farm Ponds

Antimycin and rotenone are two pesticides registered by the Environmental Protection Agency for eradication of fish. Only rotenone is economically feasible for eradicating complete fish populations and is the more commonly used compound. Antimycin can be used to kill scaled fish selectively from catfish ponds, but treatment is usually expensive.

What is Rotenone?

Using Rotenone To Renovate Fish Populations In Farm Ponds
Using Rotenone To Renovate Fish Populations In Farm Ponds

Rotenone is a naturally occurring substance found in the roots and stems of several tropical plants. Jewel vine (Derris spp.), Lacepod (Lonchocarpus spp.), and hoary pea (Tephrosia spp.) are the more common plants from which rotenone is derived. Rotenone has many common and brand names, including Cube, Derris, Fish-Tox, Nox-Fish, Prentox, Nusyn Nox-Fish, rotenone dust, and Chem-Fish. It has other uses, including use as a garden dust to control insects and as an insecticide for use on cattle, dogs, and sheep.
Rotenone works by inhibiting a biochemical process in the fish cells, resulting in an inability of fish to use oxygen in the release of energy during normal body processes. In effect, the fish suffocate due to lack of oxygen. But, contrary to popular belief, rotenone does not remove oxygen from the water. Fish treated with rotenone move to the shallow water or to the surface of deeper water, gasping for oxygen within a few minutes of exposure to the chemical. Different species of fish respond variously to rotenone, and it is a good idea to know what species are in the pond before treatment (Table 1).
Rotenone is an unstable compound that breaks down when exposed to the environment. It is ultimately converted to carbon dioxide and water. The breakdown process is rapid and is affected by temperature, light, oxygen, and alkalinity. At 80 degrees Fahrenheit, treated water will detoxify in about 4 days. In cooler water, the breakdown process is slower; at 45 °F, it can take 30 to 35 days for rotenone to detoxify. Most waters are safe for restocking within 5 to 6 weeks. In general, the cooler the water, the longer rotenone persists.
Rotenone is available at most farm and chemical supply stores. It is classified as a “restricted use pesticide” and cannot be purchased without a private pesticide applicator’s certificate. These certificates can be obtained by contacting your county Extension agent.

Preparing The Pond

Ponds of any size can be treated with rotenone, but it can be difficult to achieve an even distribution of rotenone for an effective fish kill in larger ponds or lakes. It is also expensive to treat large volumes of water. For these two reasons, it is advisable to reduce the water area and volume as much as possible before treating. This can be accomplished by draining the pond as low as possible with a built-in standpipe, by a pump, or by a siphon device. The less water you treat, the more cost-effective the treatment.

A simple siphon can be constructed to drain any pond where the ground level behind the dam is lower than the water level inside the pond. This device is constructed of PVC sewer pipe and duct tape. A diameter of 3 inches is easiest to handle, but larger diameters drain the pond more quickly. Two or more drain pipes can be used to decrease draining time. The technique is simple. Glue or tape several joints of pipe together, and install a female adaptor and male clean-out plug on one end. On the opposite end of the pipe, tie a gallon jug onto a 12-to 18-inch string attached to the pipe, then tie a 1/2- to 1-pound weight to the pipe. Locate the pipe in the center of the dam or levee, or at the point where the ground level behind the dam is lowest. Push the pipe assembly into the pond (float and weight end first) perpendicular to the dam. The weight will suspend the suction end about 12 to 18 inches below the float at the surface. Remove the plug from the near end. Allow the pipe to fill completely with pond water. When the pipe is filled, insert the clean-out plug to seal the water inside the pipe. Pick up the plug end of the pipe and carry up and over the dam to the back side at the lowest point (be sure the pipe assembly is long enough). Once the plug end is at the lowest point behind the dam, unscrew the plug and allow water to flow out, creating a siphon that will drain the pond to the level of the outside end of the pipe. If you have made good, airtight connections, the siphon will flow smoothly and continuously, until the water in the pond is lowered to the level of the outlet on the back side of the dam.

How To Apply Rotenone

Rotenone is available in a wettable powder or a liquid formulation. Liquids are easier to get into solution and provide the more reliable application for total fish kills. The liquid formulations typically contain 5 percent rotenone, although some contain 2.5 percent in a synergized form.
All formulations must be diluted with water and evenly distributed throughout the water column. The chemical can be sprayed over the pond surface or dripped into the prop wash of an outboard motor. The key consideration is to attain an even distribution; otherwise, fish may find “safe” areas and escape being killed. Application in a random “S” pattern throughout the pond will maximize even coverage.

The best time to eradicate fish from a pond for restocking is late summer or early fall. Water temperatures are at their highest at this time, and the weather is usually dry, allowing easy draining. Killing the fish at this time reduces the time between the kill and the restocking, which minimizes the chance the pond will be contaminated by unwanted fish before restocking. This is an important consideration, since the entry of unwanted species can defeat the purpose for the renovation.
Treatment rates will range from 0.5 to 3.0 parts per million, depending upon the species being killed (Table 2).
If there are any puddles or pools in the upper portion of the pond after draining, it is critical that these also be treated to kill any fish therein. Many small fish can survive in these pools, puddles, or stump holes for long periods. These must be killed to accomplish a successful renovation. Otherwise, these surviving fish can represent contamination of the new fish population, and the renovation will have been for nothing.

When To Restock

It is important to wait until the rotenone dissipates before restocking. If the kill is conducted in early fall, the rotenone should be detoxified by the time winter rains have occurred to partially refill the pond. A good general rule of thumb is to wait 1 month. A simple test can help determine when it is safe to restock. A few fish (bream, goldfish, minnows) can be placed in a small cage in the pond or in a container with water from the pond. If the fish survive 24 to 36 hours, it is safe to restock the pond.
Another reason to renovate the pond in late summer/early fall is that it coincides conveniently with the availability of fingerling bream from hatcheries. For information on selection of species and stocking procedures for farm ponds, request Publication 1892 from your county Extension agent.

Common Questions

There are questions that commonly arise regarding rotenone and its use. Some of these questions include:
Is rotenone toxic to humans? No. The toxicity of rotenone is extremely low, but, as with any pesticide, it is a good idea to handle rotenone with care to minimize contact. The rotenone formulation contains petroleum products that may be harmful. Wear protective clothing, including rubber gloves and goggles. Be sure to shower or bathe immediately after handling rotenone, and thoroughly wash your clothes before wearing them again. The label prohibits swimming in treated water until after the application has been completed.

Is rotenone toxic to livestock?

Rotenone is safe for all livestock except swine, which are sensitive to the compound. Livestock (except swine) and pets can enter the treated pond and even drink the water with no effect. For example, a 22-pound dog would have to drink 4.2 gallons of water treated with the maximum amount of rotenone to ingest the minimum safe level. EPA has stated that there is no reason to exclude livestock (other than swine) from rotenone-treated waters. As an added safety precaution, however, try to minimize livestock or pet activity in the treated water.
Are the fish safe to eat after being killed by rotenone? Although rotenone is considered nontoxic to humans at levels that would be found in a treated pond or fish, EPA and FDA have not established the maximum acceptable residue level permitted in fish for human consumption. Therefore, human consumption of fish killed by rotenone cannot be recommended.
What about ducks, birds, raccoons, or other animals that may eat the fish? This is no problem. Scavengers cannot eat enough of the treated fish, if rotenone is applied according to label instructions, to ingest enough rotenone to be harmful.
What if the rotenone leaves the pond? If rotenone is washed out or otherwise escapes the pond and enters any other body of water, it can kill fish. This is a danger of rotenone application, and it is against label recommendations to apply rotenone in situations where it can enter nontarget waters. However, the rapid breakdown of rotenone minimizes the likelihood of toxic effects downstream if applied properly in a drained pond.

Can treated water be used for irrigating crops? Rotenone has been used as an agricultural insecticide and poses no threat to crops or other vegetation. However, label directions warn against use of treated water for irrigation.
Can rotenone be neutralized? Yes. Potassium permanganate or chlorine can be used at a 1:1 or 2:1 ratio with the concentration of rotenone applied. Additionally, if fish are removed from treated waters quickly enough, they can often be revived by placing them in fresh water.

By Dr. Martin W. Brunson, Extension Leader and Fisheries Specialist, Department of Wildlife and Fisheries
Adapted from SRAC-Publication-No.-4101-Removing-Fish-from-Ponds-with-Rotenone by R.J. Sousa, F.P. Meyer, and R.A. Schnick. USFWS.


Mississippi State University does not discriminate on the basis of race, color, religion, national origin, sex, age, disability, or veteran status.
Publication 1954
Extension Service of Mississippi State University, cooperating with U.S. Department of Agriculture. Published in furtherance of Acts of Congress, May 8 and June 30, 1914. Ronald A. Brown, Director
Copyright by Mississippi State University. All rights reserved.

This document may be copied and distributed for nonprofit educational purposes provided that credit is given to the Mississippi State University Extension Service.

Everything You Need to Know About Nitrites

Nitrites – A Tenth the Level of Ammonia is enough to Kill.

i.e. 3.0 ppm ammonia is as deadly as 0.3 ppm nitrite.

Nitrites: Second Waste product in the Cycle, Low Numbers KILL!

Nitrite is an intermediate metabolite in the CYCLE. Nitrite binds fish Red Blood Cells causing gasping and “brown blood disease”. Extension agents without testing gear can make a presumptive diagnosis of Nitrite poisoning by simply cutting a catfishes’ head off, and the blood will be brown.

Fish that die with their gills flared, usually died of Nitrite induced “met-hemoglobin-emia”
Ways to combat nitrite intoxications are as follows:
1) Know the problem exists, a simple test will tell.
2) Partial waterchanges will lower Nitrite levels
3) Addition of salt (non iodized 1 teaspoon per gallon all at once) will inhibit uptake of Nitrites. (Preferred)

Interestingly, the protective function of salt lasts maybe 3-6 weeks.

If you’ve got Nitrite problems, then that means you DON’T have enough Cycle bacteria –  so if you can, BIOSEED!

4) Methylene Blue at bottle doses may also help, but not entirely reverse the Met-Hemoglobin-emia.
In many instances, the filter needs cleaning or upgrading.
Feeding should be suspended or reduced.

If you are running a drip irrigation water replacement system (CLICK), you will not need to worry about Nitrites.

Article Number Two on Nitrites

Nitrites – Brown Blood Disease

The Cycle of beneficial ammonia reducing bacteria in aquatic environments
The Cycle of beneficial ammonia reducing bacteria in aquatic environments

Ammonia is converted into Nitrite by Nitrosomonas
So, when you set up a new pond, and the fish produce Ammonia; that ammonia is reduced to Nitrite, the subject of this article.

Nitrite is converted into NitrAte (plant food) by Nitrobacter.

Nitrites cause reddening of the fins and irritation of the gills, gasping + excess mucus. A simple test kit can detect Nitrite.

Nitrites also bind the fish Red Blood Cells resulting in suffocation and “Brown Blood Disease”.
-> Nitrite toxicity is temporarily reduced by the addition of salt at one teaspoon per gallon of water.

Nitrites can be created from Nitrate under anaerobic conditions. (Deep sand, clogging filters, stalled sand filters etc.)

Nitrites can be controlled with wet-dry filtration, constant replacement of a little water all the time to the tune of ten percent per week, and traditional water changes as needed.

Nitrite toxicity is weakly reversed by addition of Methylene Blue.
+ “The reversal of Nitrite poisoning by salt is not permanent. Work at Auburn University showed the protection varied among fish species and could last up to eight weeks.” ~ Doc Johnson

+ Note From Doc Johnson
“When I have Ammonia or Nitrite problems, one of the first things I do is raise the Total Alkalinity of the pool with baking Soda, ph pills, Neutral Regulator, Oyster Shell, or similar. Then I will suspend feeding and increase aeration until the numbers come down.” ~ Doc Johnson

+ Nitrite accumulations with certain kinds of filters can be due to common undersizing mistakes. It may also be that you’re not giving sufficient oxygen or Calcium to the beneficial bacteria living in your filter. Before you get too frustrated with your filter, make sure you get some calcium carbonate for it.

Ammonia “The Silent Killer” Koi Health and Ammonia Accumulation

Ammonia is the primary chemical waste product of the fish. It’s basically fish urine. It can accumulate in ponds and cause health problems for the fish. Step Four is to assess this ammonia level with a test kit, or have someone test this for you. After assessing Ammonia levels in the pond, assure a healthy pond by doing water changes to remove the offending Ammonia, and reduce feedings in order to reduce Ammonia production by the fish. In some cases a dead fish may be decaying in the pond and cause high Ammonias. Some people use chemicals to bind the Ammonia but even though the application of certain chemicals may deceive your ammonia test kit to show a negative, the application of chemicals for Ammonia seldom results in healthier fish.

Don’t go too far into a discussion of Ammonia without also knowing about its correction by easy water changes, and Bioseeding.

From my sister-site by Frank Prince-Iles

Keywords: Considering Ammonia, ammonium water quality, the nitrogen cycle and Koi Health

Ammonia is extremely toxic and even relatively low levels pose a threat to fish health. Ammonia is produced by fish and all other animals, including ourselves, as part of normal metabolism. Such is the toxicity, that most animals immediately convert it to a less harmful substance, usually urea, and excrete it in urine.
Fish shortcut this process and continually excrete metabolic ammonia directly into the surrounding water via special cells in the gills. In a natural environment, such as seas, lakes and rivers, it would be immediately diluted to harmless levels. However, in the confines of aquaria and ponds, levels can rapidly rise to dangerous levels unless it is constantly removed, usually by biological filtration. Additional amounts are produced from decomposing fish food, fish waste and detritus.

The effects of Ammonia on fish health:

Raised levels affect fish health in several different ways. At low levels (<0.1 mg/litre NH3) it acts a strong irritant, especially to the gills. Prolonged exposure to sub-lethal levels can lead to skin and gill hyperplasia . Gill hyperplasia is a condition in which the secondary gill lamellae swell and thicken, restricting the water flow over the gill filaments. This can result in respiratory problems and stress and as well as creating conditions for opportunistic bacteria and parasites to proliferate. Elevated levels are a common precursor to bacterial gill disease.

Fish response to sub lethal levels are similar to those to any other form of irritation, i.e. flashing and rubbing against solid objects. Without water testing it would be very easy to wrongly conclude the fish had a parasite problem.

Dechlor, Dechlorinator, Sodium Thiosulfate: All Neutralize Chlorine in Fish Ponds and Tanks


What it is:
Water gets sent to your house by a municipal water company. They get this water from different sources, many of which aren’t 100% germ free. The water gets treated with chlorine so the germs die. But when the treated water gets to your house some of that chlorine resides in the water, and can kill or seriously harm your fish.

Dechlorinator binds up the chlorine, making the water safe to use.

A stronger chlorine compound, called CHLORAMINE, is used by some municipalities. Dechlor works on these compounds too, by binding the chlorine fraction. A TINY, minuscule amount of ammonia gets left behind, to be used by your filter bacteria. If you do not HAVE filter bacteria, the ammonia from this could accumulate after a major water change to a level that might be measurable. People make a big deal about it, because making a big deal out of things gets a lot of attention.

Sodium thiosulfate is a compound which is used to remove and detoxify chlorine or other heavy metals which may be used by water companies to make water safe for consumption by humans. What it’s good at:

Dechlorinator is good for removing harmful Chlorine from new water which you’re adding to your pond during a water change.


Chlorine is often used by water-treatment plants to kill harmful bacteria and spores which may be in water intended for cooking or human consumption. The amount of chlorine used by the water authority will vary by the number of spores or cysts found on routine testing. When performing a water change, you should drain down the pond. Estimate the volume of water to be replaced and apply the dechlorinator to the pond. Then begin to refill the pond. Dechlorinator is non toxic. Dechlorinator cannot be overdosed (almost).

Activated Charcoal – Carbon Filtration (Purification)

Activated Carbon – Charcoal

Activated Carbon – Detailed information – by Carl Gittings
This article was prepared by Carl Gittings in preparation for Koi Camp 2002 at Ashland Berry Farm.
Activated carbon is currently used in numerous applications ranging from the decolourisation of sugars and sweeteners, gold recovery, colour/odour correction in wines & fruit juices, to the treatment of drinking water. Even the ancient Egyptians knew of the beneficial properties that charred coal had in improving the quality of drinking water.
Activated Carbon is typically used in three different areas of aquaculture: 1) taking impurities out of water as it is brought into a facility; 2) removing halogens (any of the five elements fluorine, chlorine, bromine, iodine, and astatine that form part of group VII A of the periodic table and exist in the free state normally as diatomic molecules); and 3) removing color and metabolic by-products in re-circulating systems.
What is Activated Carbon?
Activated Carbon is a crude form of graphite and is commonly made from wood, coal, lignite and coconut shell. The imperfect structure of activated carbon, which is highly porous, is what differentiates it from graphite. These pours range in size from visible cracks and crevices to microscopic dimension. This structure gives the carbon its very large surface area, which allows the carbon to adsorb such a wide range of components. Activated carbon has the strongest physical adsorption forces or the highest volume of adsorbing porosity of any substance known to mankind (5 grams of activated carbon can have the surface area of a football field).
How is Activated Carbon Made?
A substance is first subjected to a heating process called carbonization. This forms a fixed carbon mass that is full of tiny pores. It is then activated by a second heat/steam treatment (200 -1600oC) while regulating oxygen level. This is what creates the huge internal pore network and imparts surface chemistries that give carbon its unique filtering characteristics. There are 3 main forms of activated carbon: 1) Granular – irregular shaped particles ranging in size from 0.2 to 5mm, 2) Powder – pulverized carbon, 3) extruded & cylindrical in shape.
How Activated Carbon Works
Activated carbon removes organic compounds from aquaria by adsorption and absorption principles. Both processes involve the transfer of the pollutant from the liquid phase (water) to the solid phase (carbon). Adsorption is the primary sorption mode used to remove pollutants. This attractive force forms a bond between the carbon and the adsorbate (pollutant) causing the adsorbate to adhere to the carbon. In addition, bacteria will colonize the outer surface of the activated carbon and consume some of the sorbed organics. The bacterial action also reactivated a small portion of the carbon and perhaps prevents desorption.
Absorption refers to the diffusion of a gas or compound into the porous network where a chemical reaction or physical entrapment takes place. Ozone for example is absorbed into activated carbon where it oxidizes a portion of the carbon’s surface. Ozone (O3) is reduced to oxygen (02) thus detoxified and made safe for the pond. Ozone does not accumulate or build-up in the carbon structure.
A third process called chemisorption forms an irreversible chemical bond between the carbon surface and the adsorbate. Pollutants are tightly bound to the sorbent.
All three sorption processes occur simultaneously in the pond. The sorption process takes place in three stages:
1) Organic laden water contacts the activated carbon particle.
2) The adsorbate diffuses into the porous network.
3) Sorption onto the carbon occurs.
These activities can be described as the activities observed in a parking lot. Vehicles (organics) are moving freely on the main highway (pond water). The vehicles enter the lot (pore) in search of a parking space (sorption site).
Benefits of Activated Carbon
Due to the sorption process that occur with activated carbon, it is very effective at removing toxins (insecticide and plant), some chlorine and chlorimines, and organics that may discolor your water. The overall result is an increase in water quality. The by-product of better water quality is healthier fish. The activated carbon should have a macroporous structure, Low Iodine number which is a measure of the microporosity (below 600) and a high molasses number which is a measure of macroporosity (above 400).
All carbon will release some phosphate. It is best that one looks for an activated carbon that has not been activated using phophoric acid. Phosphate levels released by Carbons that were activated by means other that using phosphoric acid are low and not harmful to the pond or its inhabitants.


Chlorine and Chlorination, Chloramines and Aquatic Life

Chlorine (You better know about this).

When water comes out of your hose, in most areas, it’s “city water”. This means that it is accumulated by and “made drinkable” by the city. Then the water is supplied to your house.

They almost invariably “chlorinate” the water. This means they add chlorine (and sometimes chloramines) to the water. These compounds are supposed to make the water safe for you to drink and use.

Chlorine and Chloramine are toxic to fish.

So; every time you add new water from the hose or the tap, you should apply some “dechlorinator” to the volumne of water you’re adding.

Dechlorinators are inexpensive and effective. It is not possible to use ‘too much’ dechlorinator because this compound, (Sodium thiosulfate) is not toxic to fish.

Experienced advice: Always treat incoming city water with a sodium thiosulfate based dechlorinator. Never skimp. You’ll hear the pundits say that you can mist or spray the water through the air into the pond and that will neutralize the Chlorine. This is true to a very limited extent and does not consider that municipalities will add variable amounts of Chlorine and Chloramine to the water depending upon how the water checks out that day. Again, to compensate this variable; always dechlorinate.

If you are using a “trickle water replacement system” in place of in and out water CHANGES you can skip dechlorinator.

SHORT AND SWEET: Dechlorinate every time you do a water change. Dechlorinator is cheap and it’s easy and safe to use.


Hydrogen Sulfide Gas is a Rare Problem But It Kills When It’s Present.

Hydrogen Sulfide is not a common problem in fish ponds, as far as we know. (It *is* a problem in fish tanks, though. Especially at a major cleanout and with disruption of the sand / fluorite etc.)

What this means to pond people though, is; pond people don’t test for Hydrogen Sulfide much, so we don’t really know whether it’s common or not.

Here’s how Hydrogen Sulfide is produced: A plant is set on the bottom of the pond. Or a huge statue. Fish wastes accumulate under the large and heavy object. Every time your spouse suggests you clean out the grossness under this large and unwieldy item, you come up with an excuse. Ooooh my back! So it doesn’t happen for a long time.

Anyway, after three years, a black stain appears in the center of the wastes trapped there, and in the black stuff, there are bubbles of gas. These are hydrogen sulfide bubbles. The smallest amount of hydrogen sulfide will start killing your fish. Especially if those bubbles are swept into the water column suddenly.

What’s happening in the stagnant media is that a bacteria exists in areas WITHOUT water movement and WITHOUT oxygen. In the opportune spaces, the bacteria make hydrogen sulfide gas.

As it accumulates in the water, the gas causes weakness, increased vulnerability to disease, and finally obvious symptoms of brain damage and death. Enough hydrogen sulfide could kill you in an enclosed space.

Clean Up

Clean up isn’t easy. If you suddenly decide to run the test for Hydrogen Sulfide and you discover that the huge statue is trapping it underneath, you can’t just go in and yank out the thing. Removing the object which is trapping the gas would liberate large amounts of hydrogen sulfide all at once; and all your fish would be dead before you could get them out of the pond.

You need to remove all the fish from the pond before the cleanup operation is begun.

SHORT AND SWEET: Hydrogen sulfide is a problem in stalled sand filters or ponds which contain layers of sediment on the bottom or in large and neglected planters.