Is there a pool volume quantitative test?

[NickJ]

For years I have wondered why there is no test for pool volume so I thought "maybe" there is and I just haven't found it so I am posing the question here for the experts.
I "think" my pool's volume is 29,000 gallons but more often than not the quantities of chemicals I add don't raise the levels as I would expect so I have begun to wonder again. Our pool is probably well over 75 years old. It had a one meter diving board which we removed and consequently is very deep - like 10 feet - at the peak of the upside down pyramid deep end, I think it is called a hopper style. I divided it into the pyramid and rectangular shapes but obviously had to estimate angles and some dimensions so I might be off. It seems to me adding a known quantity of some inert chemical that would not hurt anything if left in the water and then measuring the diluted concentration it achieved in the pool could tell you the pool's volume precisely. Of course it would only work one time unless the pool were completely drained but that is all anyone needs. Any suggestions?

 

[Newdude]

Any suggestions?

Add FC, salt, calcium or CYA. If it raised you by more than you thought it would, your volume is too low. If it didn't raise you enough, it's too high.

You're unknowingly doing the test you'd like each time.

Between rain and evaporation the pool is rarely dead on. So darn near close enough is close enough.

 

[NickJ]

Yes, what caused me to bring this up is I just added 8 pounds of cyanuric acid since my stabilizer had dropped to zero over the winter and I achieved under 30 PPM. (Still see the dot when the tube is full) The filter may still be dissolving the CYA but it has been almost 2 days. My pump is set to move 29,000 gallons through the filter daily but the water is only 70 so not warm at all. My problem with all the other things you suggested is their interaction makes it impossible to draw any conclusion but CYA "should" work to some extent shouldn't it?

 

[Newdude]

The filter may still be dissolving the CYA but it has been almost 2 days.

If you added 33ppm, it's in there. If your gallons were off by 4k, it's only be 3 or 4 ppm different and you'd never know.

How did you add it ?

My pump is set to move 29,000 gallons through the filter daily

Why ?

Turnovers are a junk requirement. You and I are neighbors with trees between us and the wind blows your way. You need tons of filtering in the spring and fall and I need none. Neither of us needs much mid season.

The chemicals need 15 mins to mix. Twice a day is even better.

My problem with all the other things you suggested is their interaction makes it impossible to draw any conclusion

FC may be depleted if you were low and it needs to sanitize things, but not if you had adequate FC in the first place.

Salt, CH and CYA all add what they add regardless of anything else.

 

[1poolman1]

For years I have wondered why there is no test for pool volume so I thought "maybe" there is and I just haven't found it so I am posing the question here for the experts.
I "think" my pool's volume is 29,000 gallons but more often than not the quantities of chemicals I add don't raise the levels as I would expect so I have begun to wonder again. Our pool is probably well over 75 years old. It had a one meter diving board which we removed and consequently is very deep - like 10 feet - at the peak of the upside down pyramid deep end, I think it is called a hopper style. I divided it into the pyramid and rectangular shapes but obviously had to estimate angles and some dimensions so I might be off. It seems to me adding a known quantity of some inert chemical that would not hurt anything if left in the water and then measuring the diluted concentration it achieved in the pool could tell you the pool's volume precisely. Of course it would only work one time unless the pool were completely drained but that is all anyone needs. Any suggestions?

Trying to be precise in quantities is not reasonable with a swimming pool. Every Certified Pool Operator course I took, when discussing chemicals and dosing, started with the premise that we are accurate, but not precise. For example, I lost an inch of water to the North wind we had here for the last day and a half. Happens a couple of times a year. Thought it was a leak until I got used to it. How could I possibly know how much water is in my pool based on any measurement.
To be accurate, we have a +/- 10% margin of error and we are good.
For example, adding 1 gallon of liquid chlorine is considered adding 10ppm (shocking 10k gallons). But that is only a good estimate as you can never know the precise amount of actual chlorine is in the jug, though we consider it as 1# if relatively fresh. It very much depends depends on how fresh it is (and the percentage on the label when fresh). How has it been stored? Was there actually a gallon in the jug? What is the temperature of the chlorine? Was it poured close to the surface or from a standing position which will allow some to gas-off from the splash? Also, adding 1 pound of chlorine (which there is, more or less, in a gallon of 12.5% liquid) is considered adding 10ppm, but if you do the math its only 8.34ppm in pure water and even less in pool water which weighs more due to all the TDS.
If you are even close in your estimate of you pool's volume, consider it 30K gallons and dose for that.
You can buy chlorine in 1# packages labeled as "shock" (shocking a pool is a process not a product), but if it is cal-hypo it is at most .72# of chlorine and if di-chlor it is .56# of chlorine.
The same applies to any chemical we add; acid, CYA, etc. And, our testing method can skew the results based on how far into the body of water we reach to get the test sample.

 

[NickJ]

I don't use salt but I did add 50 pounds of calcium chloride when TA was about 125 and it is now 225 so that might tell me what I am after. I will have to go back to Pool Math and see what it predicts TA should be after the 50 pound addition. Thanks

 

[NickJ]

I added the cyanuruc acid by first mixing the 8 pounds in hot water in a 5 gallon bucket and pouring it in the skimmer but aftet a couple of buckets of water I could not see any difference in the hot water and regular tap water so I finished with tap watre. I had to stir it a lot to get the particles suspended but am counting on the filter to catch the particles and dissolve them. Do you think 2 days is sufficient time constantly running the pump? Again the water is only about 70 degrees F.

 

[Newdude]

Do you think 2 days is sufficient time constantly running the pump?

No. It takes up to a week when granuals are dumped into the skimmer. It's mostly in your filter, and it will dissolve but will take some time.

 

[wireform]

CYA going through the filter can take up to a full week to be all in the water.

 

[NickJ]

I went back to Pool Math and it tells me to add 27 pounds of calcium chloride to raise CH from 125 to 225. I added 50 pounds 2 days ago trying to raise it to over 300 but now only have CH of 225 so I remain totally baffled. I know my pool volume calculation can't be that far off. It is a 20 X 40 hopper style pool. If I assume the deep end is wall to wall 10 feet deep it would only be 39 ,000 gallons so the fact that it is an upside down pyramid with four sloping sides down to the 10 foot depth makes 29,000 reasonable. I dumped the 50 pound bag of flakes into the deep end and brushed any flakes that made it to the bottom so it appeared to dissolve completely. I have ordered a gadget to gather pool water samples from deep beneath the surface and hope that is the answer. I am 78 and can't do it manually . I have been taking water samples right above a water return jet maybe 10" below water level under the theory that water would be representative of deep end water but maybe having just been through the filter would matter?

 

[NickJ]

Actually the gadget I ordered is the second one because the first collected too little water. Not enough for a full test of anything besides PH and chlorine. The one coming is much larger so I should be able to get deep samples if that is my problem.

 

[ajw22]

There is a Chemical Way of Calculating Pool Volume using an alkalinity test kit, sodium bicarbonate or acid, and the formula.

A Chemical Way of Calculating Pool Volume

There is a way to use pool water chemistry to calculate pool water volume without using the traditional geometric calculations. The geometric formulas are fine for pools that are traditionally shaped. However, when pools do not fall into these convenient shapes, a chemical method can be used...

www.troublefreepool.com