Estimating pool volume

[sande005]

Over 25 years ago, when I bought this house and pool, I estimated the gallons by measuring, using the pool pole as a depth gauge (and measuring it, also). The math came out to about 25,000 gal, which I've used as a basis ever since. But chem additions always seemed a bit "off" from prediction. Not by far, but I'm now in the habit of sneaking up on the final goal.

So today, I was prepping to convert to a SWCG. Pool was at 600 ppm for salt. 10 40 lb bags went in. After I give it a few days to mix, and do another salt reading, would back figuring the math give me a better gallonage? Not being obsessive, but it would be nice to see how far off, or not, my earlier amount might be.

 

[PoolStored]

After I give it a few days to mix, and do another salt reading, would back figuring the math give me a better gallonage?

Yes. You can also do this on most pH or FC adjustments. Add and test after 30 minutes for FC/pH. If you overshot, reduce pool volume by 500 gallons. If you undershot, raise pool volume by 500. Rinse and repeat until your actual and expected results match.

 

[HermanTX]

If you are using the K-1766 salt test kit, it has a +/- 200ppm (each drop is 200ppm) For 25k pool a 40 lb bag will raise salt by 191ppm so that falls within an margin of error.
Another way which may be quicker is to measure FC using the FAS-DPD as each drop is 0.5 ppm (for 10ml sample) or even use 0.2ppm (for the 25ml sample). Liquid chlorine will mix quickly 30-45 mins. So test for FC, pour in a volume of liquid chlorine and let it mix, then 45 mins later test again. Your SWCG needs to be OFF. It is not exact science but neither is measuring with a yard stick

 

[sande005]

Ooo! Numbers to play with. Figured since I was going from 600 to ~2,500 with the salt, that big a change would help hide a margin of error with the drop test. Didn't think about using Chorine, will try that too. My SWCG is on a UPS truck somewhere, so likely won't effect the readings much (grin)!