CYA to FC

[ntogrady]

Hello, I have a Taylor K-2006C test kit. My CYA is at 110 (down from about 140) after draining and filling 5 feet of water. My pool is 22,000 gallons. Free Chlorine is currently 24 ppm. I stopped using all chlorine tablets and switched to only liquid chlorine.

From what I am reading here at the Trouble Free Pool, I would need to drain my pool more to get the CYA under 90. Am I thinking correctly? I have been pouring about 1 - 2 gallons of liquid chlorine in my pool every other day just to get the algae under control. Brush once a day. It's just starting to turn a corner and not look so green. I keep draining about a foot of water once a week. My kids really want to swim now that school is out so I'm feeling the pressure to get it under control.

 

[Rocket J Squirrel]

Welcome to TFP!!

Drain more at a time. Your small drains are wasting water with less than the desired effect. One big drain of 50% would get you down to 50 or 60 CYA, a more acceptable level.

 

[HermanTX]

The only way to reduce CYA is to drain water and replace. Did you use the dilution test to find your CYA at 140 or 110? The scale maxs out at 100 so anything beyond that is a guess.
If you are confident the CYA is 110 then draining 50% of the water will get you to CYA of 50. I would drain 60% of the water.
Are you able to do that in your area?

 

[HermanTX]

FYI - the dilution test for CYA
a) Fill the mixing bottle to the lower mark with pool water.
b) Continue filling the mixing bottle to the upper mark with tap water.
c) Shake briefly to mix.
d) Pour off half of the contents of the mixing bottle, so it is again filled to the lower mark.

This now becomes your "diluted pool sample" because tap water does not contain CYA.

Now add the R-0013 as per the test to fill the remainder half of the mixing bottle.
When you do the test - multiply your result by 2.
So now if you don't see the dot at 30 but you saw it at 40 - then 80 is your CYA number (2x 40)

 

[ntogrady]

The only way to reduce CYA is to drain water and replace. Did you use the dilution test to find your CYA at 140 or 110? The scale maxs out at 100 so anything beyond that is a guess.
If you are confident the CYA is 110 then draining 50% of the water will get you to CYA of 50. I would drain 60% of the water.
Are you able to do that in your area?

Yes, that’s a good point. I am guessing. I was thinking I could guestimate past the 100 mark. I’ll try the dilution test and drain more all once. I was avoiding getting a permit to drain, which to be honest at this rate, probably wouldn’t have been all that hard given the amount of time and money I am wasting as I drag it out.

 

[ntogrady]

Yes, that’s a good point. I am guessing. I was thinking I could guestimate past the 100 mark. I’ll try the dilution test and drain more all once. I was avoiding getting a permit to drain, which to be honest at this rate, probably wouldn’t have been all that hard given the amount of time and money I am wasting as I drag it out.

Thank you both for your insight!!!

 

[PoolStored]

If you are going to replace water, consider the no drain water exchange approach:

Draining - Further Reading

www.troublefreepool.com