High CYA in drought area … alternatives to draining?

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J

JMPool99

Bronze Supporter
Jul 31, 2021
120
So Cal
Pool Size
22000
Surface
Plaster
Chlorine
Liquid Chlorine
Draining is THE way to lower CYA. I totally get that.

BUT… we have some serious drought conditions out west and many regions now have water use restrictions imposed. In short, draining and refilling a pool isn’t a cool thing to do right now (in my opinion).

Are there any alternatives? Figured it was worth asking the pros in these forums just in case. :)

Thanks !
 
How high is your CYA, and do you have a sand filter? When I bought our house with a pool with sky high CYA draining a significant portion of the pool was the only feasible method to reduce CYA. But if you are only a bit high the regular backwashing of your sand filter will accomplish the same thing, just more slowly. But obviously, this only applies if you have a sand filter and if your CYA level is not too high. As to what is too high, that is for you and the experts here to decide.

Also, does not need to be a complete drain. Filling half a pool is better than the whole enchilada.
 
My CYA is at about 88-90. It's high, but not atrocious. I'd really like it to be down around 50 (so about half where it is). It only got this high because we started off using a pool guy who threw tons of Trichlor tablets in the floater constantly. I wasn't educated then.... I am now!

No sand filter -- have a Pentair Quad 100 DE filter.

Thanks!
 
What will it cost you for about 8000 gallons of water?

Remember, the water is not 'wasted'. It goes right back into the eco-system. In your area, likely the ocean.
 
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If saving water is your primary concern, the CYA will drop in time on its own. The same UV that depletes chlorine will slowly reduce CYA. In the meantime, you could just increase the chlorine concentration to what 90ppm CYA calls for. In this case using liquid chlorine, that's 10-12 ppm. Kindof a large pool, so it might take quite a bit. Another option might be to convert to SWCG. Using a salt water chlorine generator, your CYA of 90 would work with 4-6 ppm chlorine. Of course you'd have the initial expense of the SWC device and bringing up your salt to the required level, but going forward, you've saved the world (or at least America or southern California) from manufacture of some quantity of liquid chlorine and the environmental cost of dumping 8,000 gallons of chlorinated water into the storm drain. Just thoughts.

And again, where did you get 88-90 cya. Are you sure about that number?
 
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I have a TF-100 kit and check my CYA regularly. It's been at about 90 for a couple months. I get the same results with the dilution CYA test and, amazingly, Leslie's water test comes in at about 90 also.

I've been keeping FC at about 9.0 - 11.0 -- but to your point, yes, have to add a good amount of chlorine to keep it up there so FC stays over the 7.5% of CYA amount.

I am on liquid chlorine (LC) only now. I was hoping that over a few months my CYA would drop from evaporation (pool faces south and gets filled daily) and time. I mean, it was about 100 6-7 months ago, so.... it is dropping but a pretty slow reduction...
 

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LOL - Yeah, I actually own an SWCG that's plumbedin but I've resisted. This summer may be the switch - doh.

Maybe this is a stupid question but... why is it that CYA is OK at 80PPM if you have a SWCG but with Liquid (LC) it's recommended to be 30-50PPM? I mean... in either case don't you (roughly) target FC to be about 10% of CYA. So why is a high CYA frowned upon with LC but not so much with SWCG?

Hopefully someone smart can educate me on that one :)
 
I did RO. People on TFP have mixed feelings about it. I am a fan. However, it is costly which is why many don’t do it. It is cheaper usually to drain and fill.

If you’re going the SWG route you can leave the CYA around where you are and let it continue slowly dropping. In our area, the CYA drop takes a long time (as you have noticed). Another reason to do RO or a drain/fill is to address high CH if you have that issue.
 
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JMPool99 said:
So why is a high CYA frowned upon with LC but not so much with SWCG?
Click to expand...
It's only frowned upon for what it costs you and the effort it takes. If you don't mind either, dose away at 90 CYA. But you have to maintain being above the higher minimum also, which the SWG easily does adding a little bit all day long. Dosing LC is a spike and gradual fall until tomorrow's dose. At higher FC levels it burns off faster, becoming counter productive and expensive quickly.
 
Also if you don’t have a solar cover - consider it because, based on my testing/observation, it helps slow down the chlorine burn off a bit and helps with evaporation.
 
I wouldn't spend much effort (draining, RO, or whatever) to reduce an 80-90ppm CYA -- that's a manageable level if you keep on top of it, and it will reduce on its own over time (next year or the year after you might find yourself having to add some, depending on how much rain comes).

You won't actually be using more chlorine; less overall in fact. While it takes more initially to bring it up to the higher target, the CYA buffer results in lower losses from sunlight each day so you add less to maintain. For example, at CYA 80 you might lose 2ppm FC per day, while at CYA 50 that might be 4ppm FC.

The main reason higher CYA levels (and lower FC minimums) are recommended with an SWCG is mainly because the continuous automated generation means it's much easier to be sure that you stay above the minimum, and thus much less likely that you'll need to SLAM (which is harder to do from higher CYA level). And especially when SWCGs are not as oversized as recommended here, the reduced FC loss with higher CYA makes it easier to generate enough. If you check and add manually daily that risk is similarly reduced.
 
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Fyi - evaporation doesn’t reduce cya - It’s just more concentrated & when u replace what was lost to evaporation you’re back to where u started for the most part. Only exchanging the water will reduce it- Like where it rained then you drain some or if you backwash & replace that etc.
 
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Duh... good point Mdragger88. I have a submersibable pump... maybe I'll drain off a foot or two only. I know there are some post on how to replace water without lowering the level much. Fortunately, with stupid trichlor tabs out, I've stopped the bleeding...
 

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