How much to drain to lower CYA

[WannaBEEPoolgirl]

Had the pool store open the pool 10 days ago. They came back to check yesterday and adjust and I went back over them because I want to know how safe it is. Well:

FC is 2.6
CC is .6
pH is 7.2 (yay)
CYA is through the roof—over 100. So before I SLAM, I want to lower CYA. How much water should I let out?

 

[jimbethesda]

Do the diluted CYA test to determine what your CYA is. 200 is a lot higher than 110

 

[ajw22]

You have to have an idea how much over 100.


CYA > 90 dilution Test
For CYA > 90ppm, repeat the test adjusting the procedure as follows:

1. Fill the mixing bottle to the lower mark with pool water.
2. Continue filling the mixing bottle to the upper mark with tap water.
3. Shake briefly to mix.
4. Pour off half of the contents of the mixing bottle, so it is again filled to the lower mark.
5. Continue the test normally from step 3, but multiply the final result by two.

If you need to dilute the pool water further then apply these ratios:

Pool water	Tap or distilled water	Multiply result by
1	1	2
1	2	3
1	4	5

Note that when doing a diluted test not only do you multiply the range of the test you multiply the error rate of the test, so results are a ballpark - not an absolute.

 

[WannaBEEPoolgirl]

Thanks! It’s 140 ?

 

[WannaBEEPoolgirl]

Do the diluted CYA test to determine what your CYA is. 200 is a lot higher than 110

140 is the result

 

[zea3]

You will need to drain and replace about 80% of the water to get the CYA down to 30 ppm. Would you be using well water or have water trucked in?

 

[WannaBEEPoolgirl]

You will need to drain and replace about 80% of the water to get the CYA down to 30 ppm. Would you be using well water or have water trucked in?

Well water. I can’t imagine draining 80% of the pool!

 

[zea3]

Depending on the capacity of your well, you may need to a series of drain and refill cycles to get the CYA down. Is the pool clear or swampy?

 

[WannaBEEPoolgirl]

Depending on the capacity of your well, you may need to a series of drain and refill cycles to get the CYA down. Is the pool clear or swampy?

It’s really clear! I was going to swim in it until I tested. I’ll drain for a little bit longer and then slowly fill back up. It’s only down a two inches in 2 hours.

 

[zea3]

Since your pool is clear you can work on draining and refilling over the summer and use only liquid chlorine in your pool. As long as you don't need to slam, you can run the pool with higher CYA, it will just take a lot of chlorine. You can work on replacing your water slowly and as long as you keep the chlorine up you can keep algae away. Whenever a heavy rain is expected drain off some water ahead of time and take advantage of the free water. You may want to consider investing in an SWG. You would only have to drain down to 70 ppm and no lugging bottles around!