# Thread: Help on calculating gallons that our pool has

1. ## Help on calculating gallons that our pool has

Noticed that profile signatures around here show total gallons in their pool. How can I calculate that for our pool?

Our pool is mostly rectangular, but has a spa above pool level in a corner (waterfalling into pool from spa). In the opposite corner, is a step into the deep end of our pool, and this corner is "cut off" from the rectangle.

I would probably just begin with this formula:

Length x width x ( ( depth of deep end + depth of shallow end) / 2)
To give me volume of our pool in cubic feet. Just need this converted to gallons. Would this suffice, or should my calculation be more precise for that when I share this information to local pool supply stores, this forum, etc?

2. ## Re: Help on calculating gallons that our pool has

adding photos for clarity to what I am referring to

3. ## Re: Help on calculating gallons that our pool has

Have you seen the gallons calculator in the pool calculator in pool school?

And you gotta allow for how much that gator drinks in a day too!

4. ## Re: Help on calculating gallons that our pool has

Yes - the link was down previously - now it's back up.

Our pool is 13.5 x 30, and depth is an estimate (3 feet shallow end, 8 feet deep end, to make average depth about 5.5), it came out 16,700 gallons. However, our local store has a history on our pool from previous house owners and it is shown as 20,000, so I'm not sure if that is an estimation as well. There is a 2,300 gallon difference here - is 2,300 gallon difference significant when discussing what chemicals to buy for our pool maintenance needs?

I guess that gator drinks 2,300 gallons, lol.

5. ## Re: Help on calculating gallons that our pool has

There's about a 1500 gallon difference from what the pool calc says mine is vs. what the manufacturer says. Split the difference and treat for that-should give you a real good idea on the FC test. Got a TF-100?
Those "local store" numbers are probably the worst ones.

6. ## Re: Help on calculating gallons that our pool has

I ran the numbers with the calc to get close, then treated according to the pool calculator. I adjusted the gallons for the pool until it matched what I was feeding the pool in chlorine. Probably more accurate than using the measurements!

7. ## Re: Help on calculating gallons that our pool has

Originally Posted by RobbieH
I ran the numbers with the calc to get close, then treated according to the pool calculator. I adjusted the gallons for the pool until it matched what I was feeding the pool in chlorine. Probably more accurate than using the measurements!
Sounds like something I want to do, but I'm not really following - can you expand a bit about this methodology? Thanks in advance

8. ## Re: Help on calculating gallons that our pool has

Originally Posted by cflannagan
Originally Posted by RobbieH
I ran the numbers with the calc to get close, then treated according to the pool calculator. I adjusted the gallons for the pool until it matched what I was feeding the pool in chlorine. Probably more accurate than using the measurements!
Sounds like something I want to do, but I'm not really following - can you expand a bit about this methodology? Thanks in advance
The idea here is that adding a known amount of a chemical will have a predictable effect on your test measurements. For example, if you add 1 gallon of 5.5% bleach to a 10,000 gallon pool, your FC will increase by 5.5ppm (until it gets eaten by sunlight or algae). Assuming you have a clean pool and you do this in the evening, if you have to add 1.5 gallons to get a 5.5ppm increase, then you must have 1.5 x 10,000 = 15,000 gallons in the pool.
--paulr

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