pH Pills were pretty when we started making them in muffin tins then they were ugly and big for ponds...

Well, it's been interesting preparing the report on the "pH pill". Some of the initial (and follow-up) research has yielded some interesting data. I will go through it all for you, from basics to "brass tacks"
The "pH pill" is a home-made pill, puck, or chunk, of white chalky material you can toss into the pond or aquarium, and it will slowly dissolve, liberating carbonates, Calcium, Magnesium and gypsum. The dissolution of the "pH pill" increases hardness, alkalinity and more in the water being treated.
It remains to be seen, but some enterprising individuals plan to borrow this technology and incorporate some medications into it for slow infusion into a system. For example, Dimilin (Diflubenzuron) would be ideally suited to this form of dosing.
TRADE SECRET: The "pH pill" is composed of nothing more than pure Plaster of Paris. For the research we did, we used high grade Plaster of Paris purchased at Home Depot. The ingredients are:
C.A.S. Limestone 50%
C.A.S. Gypsum 50%
…with no hardeners or setting agents added. You should be cautious to read the contents label, because some of the plasters-of-paris I saw at hobby shops had stabilizers, binders and hardeners to hasten the set up of the plaster.

Wanna hear something unbelievably stupid? The pundits (who didn't have ANY idea what CAS stood for) decried this information saying you don't want to put Calcium Sulfate in your pond!!!! Remember these are the 'know-it-all' ass hats that are saying this. CAS stands for Chemical Abstracts Service. Not calcium sulfate.

There are precautionary statements on the bag, which suggest the dust from this compound can be eye irritant and should not be breathed. The bag weighs twenty five pounds and cost under nine dollars.

We mixed up the Plaster of Paris using regular tap water. Before it had a chance to set, we poured it into cupcake tins, making our initial batch of test-pills the size of small hockey pucks. [Two-and-a-half inches in diameter and one inch thick). It was very difficult to get them out of the pans, so we tried plastic containers the next time and had much better results.
From a friend/hobbyist: 12/19/98
"I'm using the pH Pill in my 500 gal. hospital tank (in which I always have trouble keeping the total alkalinity up) and it seems to be working just fine. BTW, a styrofoam egg carton works well to cast the Plaster of Paris into. The resulting puck has good surface area and can be easily broken into various sizes (now have 13 lumps in the tank - seems stable). I will try a little Pam spray as a release agent in my next casting (I'm using an 18 egg carton and Home Depot PP - works well.)" ~SC
Plaster of Paris sets up in less than ten minutes, so if you're not pouring pretty expediently, you'll have a chalky, lumpy mess, which will not pour. We found we could make it as thin as we wanted and it would still set up and harden. The more water in your mix, the more shrinkage will occur as it sets up. The quality and performance of the final product is unaffected.
In total; four ponds, and twenty-one aquaria were treated with varying numbers of these "pH pills" and the results have been very good. No toxicity or ill effect was noted in any dosing regimen.
We put whole-pucks into thirty-gallon aquaria, with tropical and coldwater fish, and they worked fabulously, lasting up to seventeen days. The PH of tested systems was always near neutral and best of all, water clarity was enhanced. More on this later.
We put whole pucks into thousand-gallon-ponds and found they dissolved fairly rapidly, but were not adequate to support the pH under heavy loading. In one pond, of twenty two hundred gallons, it took six or eight "pH pills" to support the pH and the pucks lasted nine days. It is now our recommendation that for large ponds, you can mix up a shallow plastic pan full of the Plaster of Paris, then liberate the entire slab from the pan when it is completely dry. The slab is struck in the center (or can be scored for neat breaks) and larger pieces should be used in larger ponds.
My own pond is now being supported by two pieces which are one-and-a-half inch thick and measure six-by-nine inches across the face.
We did notice that the dissolution of the "pH pill" can be slowed by the
addition of other carbonates to the system. When water is pre-treated with Baking Soda or Neutral Regulator, the "pH pills" lifespan is increased.
Placement of the "pH pills" is paramount. They MUST Be employed in the main water flow of the system. This can be either the pulling or pushing segments of the plumbing. For example; in my main system, the chips are used in the skimmer and a slow draw of water ensures their eventual dissolution. In aquariums, if you're using undergravel filtration, best results are had when you lay the pill on the gravel near the "stacks". You can even put the "pH pill" in the filter box hanging on the back if you use that type of filter.
There are some precautions concerning the use of "pH pills".
First, to get good results, you must place the "pH pill" in the main pull or push of the water way as we have already mentioned..
Second, do not breathe the powder, or allow the dust in your eyes.
Finally, do NOT use the "pH pill" until it is chalky, and bone dry. If it still feels slick or cool to the touch, it may not be "cured" and it will comprise a liability to the fish in that condition. When completely dry, the "pH pill" weighs relatively little, and is chalky and dry. When placed in the water, thousands of tiny bubbles will escape it's surface. This is perfectly normal and will subside once it's let off its trapped air.
One interesting note on the "pH pill" concerns its composition. The "pH pill" is made of pure limestone (75%) and Gypsum (25%). Dr. Claude Boyd discusses the use of Gypsum to clarify pond water in his book, released through Auburn University entitled "Water Quality in Ponds for Aquaculture". The book is superb and it's availability from Auburn is discussed in the resources pages of my textbook, Koi Health and Disease.
In Dr. Boyd's work, he found that Gypsum was a very effective water clarifier, and we have found this to be true in our own testing of these home made "pH pills". Dr. Boyd's book mentions and compares the clearance of certain turbidities with Gypsum so the benefit is not universal, and depends upon the cause of the particular turbidity. The turbidities I have found it to clear most propitiously are suspensions of the pond's organics and "fines". I doubt Gypsum's ability to clear a bacterial haze.
Limestone is nothing more than pure Calcium and Magnesium carbonate. The limestone used in our Home Depot Plaster of Paris is extremely clean-dissolving, unlike agricultural or dolomitic Limestone. The dissolution of the "pH pill" liberates Calcium and Magnesium, which increase water hardness and is beneficial to juvenile fish that can use aqueous Calcium for bone building. The pill also liberates pure
carbonates, which stabilize and actually increase pH. I could not raise the pH of any system tested above 8.3 regardless of how much "pH pill" I used.
To test the higher end safety margins of the home made "pH pill", I simply put three pucks in a ten gallon facility and had no mortalities among the following species: Goldfish, Koi, Tetras, White's Tree Frogs, Alligator Snapping Turtles, and Plecostomi.
To close this discussion, I would mention that graphics (pictures) in support of this technology are available at phpill. I encourage you to click over there soon and see the actual plaster used, the pucks we made and the systems tested.
I do not recommend that this technology is a replacement for pH monitoring. It could [unfortunately] evolve that folks are using the "pH pill" and not checking their alkalinity or pH. The assumption would be made that in the presence of a "pH pill" there can be no pH crash and that the pH is optimal. Indeed, depending upon the start-condition of your water, the "pH pill" may be entirely unnecessary or even harmful. [For example, hard water areas].
But in this technology, we do have a back-up means of maintaining a suitable pH for Koi and Goldfish with the simplicity of manufacture, and an element of affordability which make it a treasure. I hasten to assure you that I still check pH, I still use neutral regulators, but I no longer worry that I am going to miss a day of testing and suffer a pH crash. The use of sufficient "pH pill" material, whether used as pucks or slabs, obviates this possibility.

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"It turns out that if your system is grossly overloaded, or if you're retail, the pH Pill may not dissolve fast enough to support the PH against high CO2 - carbonic acid loading. You may either need to use more pieces than the average hobbyist or more work might need to be done to find a carbonate that dissolves more responsively." ~ Doc Johnson
===DR. ERIK L. JOHNSON ===
"Using plaster of paris other than the one clearly denoted at right is a fool's way to kill fish. Don't do it!" ~ Doc Johnson