# Thread: Newbie here need to Partial Drain and refill

1. ## Newbie here need to Partial Drain and refill

How to calculate an 18 X 38 Grecian for partial drain/refill???

2. ## Re: Newbie here need to Partial Drain and refill

Welcome to TFP !!

Here http://www.poolcalculator.com/

3. ## Re: Newbie here need to Partial Drain and refill

Thinking we are having copper problems.

4. ## Re: Newbie here need to Partial Drain and refill

How to calculate an 18 X 38 Grecian for partial drain/refill???
I have the same size pool although mine actually measures 18 x 37. The corners are 5 foot reliefs.

18 x 38 = 684 sq. ft. The corner relief subtracts 50 sq. ft. Your pool surface is about 634 sq. ft.

Water is 7.48 gallons per cubic foot. That means that for every foot of depth you have 4,742 gallons. 634 x 7.48 x 1 = 4,742 gallons. Two feet is 634 x 7.48 x 2 = 9,484 gallons.

Assuming you have a shallow end, the easy way is to stick a tape measure into the pool against the bottom and measure the water level drop. The other way is to measure from a fixed location like a return or the skimmer.

My CYA was too high to measure so I'm on my second partial refill of a 16,500 gallon pool. The pool calculator is great, except I have a big shallow end so the average depth is hard to guess. I'm also an engineer and I like the math.

Hope this helps.

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