Please help estimate pool size

[2001rotax800]

I am ussually pretty good with numbers, but this one has me bothered. I have a 18x36 humpback kidney IG pool with a 6' deep end. I have read a couple different estimates on capacity that range from 12,000 to 15,500. Now I figure this year I would try to nail it down. Before adding any salt it was 1720ppm, then I added 400lbs, it is now ay 4520, measure by salt test strips. I know there are not precicse, but it should get me closer than I am now.

Could any one help me and explain the fourmula that could estimate my pool capacity, thanks

 

[RobbieH]

So pretend it's 12,000 gallons. Go to poolcalculator.com and plug in pool size of 12000, start salt 1720, and make goal 4520. If the amount it says to add is not 400 lbs, mess around with the pool size until it is at or near 400 lbs. You may need to do your chemicals a few times like this until you get it just right, but this method is how I got my pool size accurate, at least for the pool calculator.

Of course if the pool size is way out of line, then something was missed along the way.

 

[woodyp]

Mine is 16x32 oval 4 ft. deep flat bottom and is just over 12k gallons. Yours is more for sure. Should be closer to 15 easy. But play with the chemical levels and see what they produce. Don' overshoot to begin with though.

 

[2001rotax800]

Man your a fast typer, that is just where i came from.

I did the exact thing you said, I started with 1720, and ended with 4520, it is telling me 17,000 gallons, does this sound correct?

 

[JasonLion]

Yes, your salt test says 17,000 gallons. But keep in mind that using salt to measure the pool size is +-4,000 gallons because the salt tests are not very precise.

The best way to refine an estimate is to use a large number of chemical additions over time and watch for trends of being either consistently high or consistently low.

 

[RobbieH]

What we all said And like stated, make sure you undershoot for a while until you get it nailed, it's a whole lot easier to add more chemical than it is to remove it, cheaper too!

 

[Puffin]

Here is an older but interesting thread discussing methods of estimating pool size http://www.troublefreepool.com/estimating-a-free-form-pool-volume-t11772.html

 

[Flotsam]

Try and get an accurate sketch - to scale - of the surface area, then break it up into sections.

Remember - Length X Width X Depth = Volume. (Or Surface Area X Depth = Vol.)

Here's how I did it: