Chemical Calculation of Pool Size - possible alternate?


Active member
Jun 19, 2014
Grapevine, TX
Pool Size
Liquid Chlorine
SWG Type
Pentair Intellichlor IC-40
I just read the thread on A Chemical Way of Calculating Pool Volume, including the various comments about its complexity, color matching issues, and the required amounts of chemicals and water.

I don't claim to have ANY expertise on this, but I do have an irregular-shaped pool and curiosity about my pool's actual volume is, so the topic is of interest to me, and I had a couple of thoughts after reading all of that:

1. A concern was expressed about color matching the two (before/after) tests because the time delay could cause the first test to undergo a pH change (affecting the color) by the time the second test is completed, thereby creating an opportunity for error.

Wouldn't it be more effective to instead just take a photo of the result of each of the tests upon completion (being sure to do them at the same place, under the same lighting conditions, and using the same camera) and then just compare those photos? It seems like that might alleviate the pH/time issue.

2. At least for those of us who aren't using Bromine in our pools, might an alternate method be to add a known amount of Bromine to the pool, then measure the Bromine concentration and use that result to calculate the pool volume?

I really don't know much about use of Bromine or what it otherwise might do to the water balance in the pool, how long it might "stick around", etc., so there might be a better "new" additive to use for this approach. But it just seemed to me that it would be simpler and maybe more accurate to add something new into the pool, then measure the concentration of that new chemical to determine total pool volume than having to instead deal with calculating the change in a chemical property that already exists in the pool.

I am curious to learn what someone who really understand pool chemistry thinks about the idea of adding Bromine (or something else that's not already in the pool)P, and then calculate pool volume by reference to the concentration of the added substance.



Mod Squad
TFP Expert
Bronze Supporter
May 3, 2014
Laughlin, NV
Pool Size
Salt Water Generator
SWG Type
Pentair Intellichlor IC-40
As long as your pool water is algae free, you can use the FAS-DPD test for FC. After sundown, test your FC and record it, then add enough LC based on PoolMath to add 2 ppm of FC. Circulate the pool for an hour or so. Then test for FC. Use the difference in FC to narrow your volume.

This must be done after sundown. That way, there is no FC loss due to UV. And if your pool is TFP clean, there is no loss to organics, either.

Only variables beyond pool size is strength of chlorine and testing.
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