The company I work for has been dealing with a lot of ammonia problems in customers pools, and over the last 2 years, this forum has been a great resource for info on ammonia, causes, and treatment.

I've made a small calculator for ammonia, it is used with the Aquarium Pharmaceuticals Ammonia Drop Kit.

It's a bit buggy (I'm a pool guy, not a programmer), and it's Mac only.

Welcome to TFP!

Since I don't want to take a chance of getting a computer virus, can you tell me what the calculator is doing? After all, what is there to calculate with regard to ammonia? It takes 8-10 times the ppm N reading from the ammonia test kit to get rid of the ammonia with chlorine. What more is there to calculate?

That's pretty much it. It accepts pool volume, ammonia level, and doses the amount of 12.5% liquid required to break the ammonia. My employees use it a lot.

And thanks for all of your great info on tfp, chem geek, your ammonia info has saved a lot of my customers a lot of headaches.

If the ammonia comes from bacterial conversion of CYA into ammonia, then it can take more chlorine than implied by the ammonia test which is really a minimum bound. The reason is that there can be partially oxidized CYA that doesn't show up as either CYA nor as ammonia. So if you know the amount the CYA dropped by such bacterial conversion, then this gives you an upper bound of how much chlorine may be needed which is around 2.5x the CYA level drop as cumulative FC.

A summary of my own experience with this in this post shows that the ammonia reading only implied perhaps 20 ppm FC that would be needed plus the 6 I added before reading ammonia, so 26 ppm total. However, it actually took around 56 ppm FC cumulatively added before things got stable and this amount of a theoretical 23 ppm FC was close to what was predicted based on the CYA level drop of around 20 ppm.

A better way to determine the chlorine demand is to do a bucket test since it is just a mini-version of what goes on in the pool. Every 1/4 teaspoon of 6% bleach in 2 gallons of pool water is 10 ppm FC. Or you can just do as I did and keep adding chlorine frequently almost every hour, mostly in one day.

Richard