“PH Pill” The Hedge Against Crashing pH

I’ve written about pH Pill many times and even illustrated the document but recently I took it to the next level and I have had great luck.

PH is the measurement of the “acidity” or “alkaline-nature” of water.

You can measure this value very easily. And even if you don’t understand the Michalis-Menten Equation, you can control and safeguard the PH easily.

Who cares? Well the fish do. And all you need to worry about is keeping that number above 6.8 and under 8.0 for Koi and most pond and aquarium fish.

If you’re keeping Discus, Angelfish, or brackish water fish including the African Cichlids then you should already be an expert on all this. Or else you’ve lost a LOT of your fish since you started.

So check your PH and make sure it’s in the safe zone for the fish you’re keeping.

The best way to “change the pH” to a suitable, neutral value is SeaChem’s Neutral Buffer: because it works, and is VERY cost-effective. There are companies selling liquid products and you will go broke.

The thing people say about SeaChem Neutral Regulator is that it contains Phosphates which are “bad” but I say, “Not if you’re controlling your lights ad daylength to below 14 hours a day.

(Phosphates can contribute to algae overgrowth if you’re reckless with the tank’s daylength and light intensity.)

Still, constant production of carbon dioxide by literally every organism and plant in the tank (at night) are chipping away at the pH “Buffering capacity” and sooner or later the pH is going to fall.

Sometimes people just put a pinch of SeaChem Neutral Regulator in the water at random intervals and have success.

I like a Buffer I can actually SEE and that’s where “PH Pills” come into play.

This is a “PH Pill” made with Plaster of Paris and is dried completely and can be placed in the tank to prevent pH crash.

PH Pills are made of PLAIN “Plaster of Paris” without accelerants, colors, plasticizers or other shananigans.

I buy mine at Home Depot. It has to be plain Plaster of Paris with only two ingredients.

Home Depot plaster of Paris contains two ingredients, basically Limestone, Calcium carbonate.

The plaster is mixed up in a ratio of TWO PARTS Plaster of Paris and ONE PART water.

It says that on the label. You can mix it and use it in 6 to 15 minutes. It sets in 30 minutes.

What I have done lately is mix up my ph pills in a ziploc bag. It works FANTASTIC.

Mixing Plaster of Paris in a ziploc bag saves you dirty bowls, implements and splashes. If you’re careful you won’t even have to wash your hands!
Ziploc contains 2 Solo Cups of Plaster of Paris mix and 1 Solo Cup of cool water.

Mix well in the bag. You can knead the bag and jostle it on the counter.

When there are no clumps you can pour it into your cupcake tray. I really like the SILICONE CUPCAKE PANS. The reason for this is because Plaster of Paris sticks to everything but Silicone. So you can make them in silicone trays and they pop right out.


The above should be a video of the mixture being “mixed” on my countertop.

I pour a cupcake portion FULL for “pills” intended for 20-30+ gallons but I fill some 1/3rd full for thinner “pills” I’ll use in smaller tanks.

In just 20-30 minutes the PH Pills will “set up” and you can pop them out of the cupcake trays for faster drying.

I’ve dried them in the microwave before. It works well except for one thing: If you put the pills on something combustible, for example a wash cloth or towel, the pH Pills with conduct so much heat the towel WILL catch fire.

When you open the door of the microwave during drying, the pH Pills will be steaming.

After you dry them (it’s optional just to leave them on the counter til they dry) –  you ABSOLUTELY HAVE TO MAKE SURE THEY Are DRY!

If the pH Pill isn’t dry you will know it a couple of ways.

If the pH pill is quite dry it will bubble when dropped into the tank.

If the pH pill isn’t completely dry it will turn into white goo, or white sludge on the tank bottom where it lands. Conceivably it could hurt the fish.

A pH pill feels “light’ and chalky. So when you pick it up you should be thinking “It looks heavier than this” and should NOT be cool to the touch.

If you’re in doubt, bust one open and see if the center is still greyish, indicating incomplete drying.

These are not at all dry and were popped out of the cupcake tray to increase surface area for drying. this batch will just air dry. You can microwave the pills for faster drying on NONcombustible plates or trays.

When the pH Pills are completely dry they’re ready for use. I like a nice, thick pH Pill from a cupcake try in ay tank of about 30 gallons. Some people break one up and use it in a couple places in the tank. Cool.

I use half of a ph Pill (or just a thin one) for anything under 15 gallons.

The PH pill will dissolve quickly if the aquarium water “demands” a lot of calcium or carbonates. If the tank doesn’t actually consume calcium or carbonates, or there’s enough being supplied by a limestone aggregate gravel, it won’t dissolve.

If you put the pH Pill in the water flow (for example in the filter or next to an airstone) it will dissolve faster, and it will dissolve needed or not. That’s “pretty okay.”

If a PH Pill gets covered in Algae, it will lose it’s direct contact with the water, it’s dissolution will be drastically impaired and it will not protect against pH Crash.

You just replace the PH Pill whenever it dwindles to a tiny size or is entirely consumed.

Doc Johnson’

This was not written with AI and represents decades of experience. It absolutely will be cannibalized by “reword bots” for other advertising websites and even reworded into e-books sold on Amazon. Severe measurement and other errors will result and I am NOT responsible for the content once the Russians have stolen and reworded it for their ad-sites.


Author: Dr. Erik Johnson
Dr. Erik Johnson is the author of several texts on companion animal and fish health. Johnson Veterinary Services has been operating in Marietta, GA since 1996. Dr Johnson graduated from the University of Georgia College of Veterinary Medicine in 1991. Dr Johnson has lived in Marietta Georgia since 1976.