CYA - High Level

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MisterMister

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LifeTime Supporter
Mar 3, 2008
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Pelham Alabama (Birmingham)
Hello to all,

I just started to open my pool for the summer, with a growing and hopefully better understanding of pool chemistry. But I do still need some guidance. On Saturday, I also installed, with the help of an electrician, my new Auto Pilot SWG. I did a water test with my new TF kit, which by the way, I like alot. Now, I've added NO chemicals to my pool as of yet, and trying to understand where to start. The water itself is surprising clear, but I would say significant algae on the bottom. The water is uncirculated, due to pump issues, or maybe something else. I have a thread open in the pool repair section of this forum. Below is my findings.

FC - 0
CC - 0
TC - 0
PH - 7.2
TA - 110
CH - 90
CYA - Guessing 180 or 200. This one has me the most concerned on how to proceed. I believe it to be way high. In the TF kit, looking in the tub until the black dot is no longer visible, it becomes not visible quick. Maybe half way from the bottom to the 90 line. Maybe not even half way, but close. The solution is very cloudy.

So, how do I lower CYA. Chemically, or as I think I've read, removing/replacing pool water?

Your help is greatly appreciated,
Mister Mister
 
Jason, dang brother, you are everywhere.

Is the CYA being that high something you hear of regularly, or from people like me who didn't know any better? How much would you guess I should pump off, half?? If half, is that safely done with a vinyl cover?

Also, remember for my other thread, the pool has not been circulated. Should I get the circulation issue resolved and do a retest? I guess that is an obvious Yes, due to needing the pump to get the water pumped off. But would uncirculated water possibly cause the CYA to be high? Maybe I should just wait and see.

Again, thanks for your help.

Mister Mister
 
Don't believe the CYA number till the pump has been running for more than an hour and the water is very clear. So, yes wait.

The simplest thing to do is to fill at the same time you are draining. The water level stays more or less constant and there are no worries about high water table problems. This approach uses about 1.5 times as much water for a 50% replacement as you would use the other way.
 
MisterMister said:
Is the CYA being that high something you hear of regularly, or from people like me who didn't know any better? How much would you guess I should pump off, half??
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Based on what I have seen, and Jason might say differently, high CYA levels are the result of those of us who didn't know better. Upon the purchase of a home with an existing pool, I assumed care of the pool on my own and learned as I went until I found TFP and saw the light. Had I not found TFP, I would have continued to have high CYA levels and probably would have fought algae blooms caused by reasons I did not understand. My CYA levels were high at 110 ppm initially and were no doubt caused by the use of 3-inch trichlor pucks used in my in-line feeder. The thing is, no one seems to explain CYA to you at the pool store. The only thing that I an countless others knew in the beginning is that "I'm out of chlorinator pucks so I gotta go get some more." You go to the pool store, plunk down $70, and take the bucket home and proceed to refill the floater/cansiter. Your TC and FC are great on paper but your CYA continues to rise through the roof because no one told you that CYA stays around. In fact, no one ever mentioned CYA at all. Then, you get algae and cant understand how that can be especially when your TC and FC show therapeutic. Only when you finally learn that the more CYA you have in your water, the more chlorine it will take to sanitize, will you come to understand the issue and the issue is that stabilized chlorine sources, although convenient in the short term, cause long term problems. Bottom line is I am glad that I caught my CYA issue when I did.

Jason will give you the expert lowdown here in a bit I am sure but I imagine that if your CYA is indeed around the 200 range, you are probably going to have to drain at least half and replace. Then you are going to have to shock with bleach based on the numbers on the CYA/chlorine conversion chart in the stickies to the shock level required on your new CYA level which, for a SWG pool should be around 80 ppm.

Learning as I go. :-D

Good luck!

Craig
 
Can't a high CYA reading also be falsely raised/elevated by algae particles? Thought I read that somehwere. Moreover, CYA can also be degraded by algae. Don't go changing the water yet. Get your filter/pump issues resolved, clean up the algae issue. Retest CYA then.

My pool actually prefers a higher CYA level.....around 70 or so. It's in full sunlight. When I had the CYA down to 30 or so, I was adding gallons of bleach every evening. With CYA of 70ish, I was adding bleach every other evening. Never had issues with algae, never had skin sensitivity issues, etc.
 
ivyleager said:
Can't a high CYA reading also be falsely raised/elevated by algae particles? Thought I read that somehwere. Moreover, CYA can also be degraded by algae. Don't go changing the water yet. Get your filter/pump issues resolved, clean up the algae issue. Retest CYA then.

My pool actually prefers a higher CYA level.....around 70 or so. It's in full sunlight. When I had the CYA down to 30 or so, I was adding gallons of bleach every evening. With CYA of 70ish, I was adding bleach every other evening. Never had issues with algae, never had skin sensitivity issues, etc.
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I think that I remember seeing something about this. Something along the lines of CYA actually being consumed in some fashion by algae over the winter in a closed pool.
 
Jason,
You have just described my situation PERFECTLY. I could not have typed it better myself. At first, I want to get furious with the pool store, then I figure it was mostly my ignorance. But I'm still a little furious with the pool store allowing me to proceed down the wrong path. And they knew it, regularly testing my water. NO MORE. With the help of TFP, and my better understanding, I feel like a free man. If I can just clean up my mess, it will all be better.

Thanks to you and thanks to all,

Mister Mister
 

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Yes, the CYA level will read high when there is any kind of murkiness, algae or otherwise.

Yes, CYA sometimes disappears over the winter. There are also occasional reports of CYA going down during major algae problems, but most of those turn out to be caused by water replacement.
 
Now, in my case, my water is amazingly clear. I can see the sides of the pool with amazing clarity, but I do have a "generous" layer of algae on the bottom, and the deep end side sloops. But again, the water is uncirculated, and once I do circulate, I'm sure the layered algae with murky the water. I'll get my pump issue corrected, and proceed.

Mister Mister
 
I'd bet your CYA is that high. The test is, of course, based on the turbidity of your water after the reagent is introduced. If you start with clear water in the tube, I don't believe the outcome is affected significantly.

Is there a history of using tri-chlor pucks? That's normally the way that pools get too much CYA.

Naturally, you have to get that pump running first but, once that's fixed, I think you'll want to drain some water.
 
Ok, I have my pump issue resolved. :-D

I haven't taken a subsequent CYA reading, but I am convinced it is way high, maybe 160. I will verify that later in the week. My plan it to take care of my CYA issue and algae issue this weekend, when I have continuous time to battle it. I plan to turn the pump on Friday evening, and test CYA Saturday morning (after circulation). With the assumption the CYA is still in that range, with the significant layer (guessing 1inch) of algae on the bottom and slopes, what is your opinion the course of action should be?

1. Replace half of pool water with "fresh" water to get CYA in the 70 range, then attach the algae. This way just seems to be the best way to me. But I believe someone previously recommended taking care of the algae first.
or
2. Clear up the algae first with probably more chlorine, the replace the water to fix the CYA. To clear the algae, my plan is to use the remaining 1/2 bucket of Leslie's Chlor Brite chlorine, then I guess switch to bleach. The whole bleach thing is a little freaky to me. But hey, I'm ready.

Now, my TA is high at 110. Should that be a secondary fix. I've read to use baking soda (or soda ash TA&PH) to raise TA, how does one lower TA. I guess this question is probably irrelevant due to pumping off half the water for the CYA issue.

Another note, water temperature is 60.

Thanks for your help.
 
Chlor Brite is dichlor, which contains CYA, so using Chlor Brite is only going to cause more trouble.

Best to lower the CYA level first. Otherwise it will require immense amounts of chlorine.

I wouldn't worry about TA being 110. That isn't bad. Do be sure to test it again after the water replacement. There is an important distinction between acceptable and ideal. Having TA at 110 is acceptable in most situations. Having TA a little lower is ideal, but there is no point in putting any real effort into lowering TA unless it is further off than that.
 
Great, thanks Jason. That was what I was thinking also. But I had thought I had read somewhere the opposite. I'll take care of the CYA issue first. Also, thanks for the TA info.

Looks I'm off to look for a cheap bleach source. That stuff needs to be sold by the bucket, or barrel.

Thanks,
Mister Mister

FOR SALE - I have a GREAT DEAL on pre-owned but unused Chlor Brite, and those freaking pucks. CHEAP!!!
 
If you have plenty of water, I suggest trying to vacuum to "waste" as much of that dead algae as you can. You won't get it all but it may save you several backwashes. If you're short on water, I think I'd vacuum it into the filter and then backwash when your filter psi goes up by 30% or so. (that's a rough guideline). Go slowly so you won't stir it up too much.

Then, when you got all the gunk out manually (or as much as you reasonably can), start your chlorination.
 
ivyleager said:
My pool actually prefers a higher CYA level.....around 70 or so. It's in full sunlight. When I had the CYA down to 30 or so, I was adding gallons of bleach every evening. With CYA of 70ish, I was adding bleach every other evening. Never had issues with algae, never had skin sensitivity issues, etc.
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We found that a higher CYA level of 60-80 ppm does in fact lower chlorine consumption from breakdown from sunlight more than linearly which means that even keeping a higher FC level at the higher CYA level you still come out ahead. We don't know for sure why this is -- my hypothesis at this point has to do with CYA (and chlorine combined with CYA) absorbing UV from sunlight protecting lower depths and that circulation isn't perfect between the surface and such lower depths (basically, the industry chart and theory of chlorine half-life vs. CYA is wrong).

Having a high CYA level with to low an FC level does not guarantee an algae bloom. Algae also needs food so if phosphate or nitrate levels are too low, then algae can be inhibited. Algaecides will also inhibit algae growth (i.e. PolyQuat 60 or copper). So it's not a simple relationship. Nevertheless, if one maintains an FC level appropriate to their CYA level, then algae growth is inhibited in all but the most extreme cases (such as extraordinarily high phosphates > 3000 ppb).

Richard
 

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