Shocked how much CYA was added in 2 weeks. newbies take note

miwitte

Well-known member
Sep 4, 2015
105
Charlotte,NC
CYA was my epiphany at understanding why i had issues every single year. You get a cloudy, green pool all of a sudden, your free chlorine is spot on, all the chemicals look good so you go to pool store. They sell you algecide, shock, water clarifier etc. Pool looks great again but the cycle repeats maybe 5 or 6 times a year and years go by you spend lots of money on "recommended fixes". My aha moment came when I went to pool store and one of the guys said your CYA is way off the chart you'll have to drain pool.

So I started doing research on high CYA and stumbled upon this site. CYA CANNOT be removed from water, only diluted by removing water and refilling. After getting a real test kit, my best guess estimate was my CYA was 4-500 or more by diluting my test sample. The question for me was what the heck is CYA and why its important and why too much is bad. Really bad.

Ill do this in layman terms, so think of CYA as a chemical that prevents sunlight from affecting the free chlorine (FC) in the pool. Can you run without CYA? You should'nt, you will go through tons of chlorine on a daily basis due to sunlight and also have ph and water balance issues. Recommended dosage here at TFP is to keep it 50-60 ppm. If you look at the CYA chart Chlorine / CYA Chart - Trouble Free Pool
You will see at higher levels the recommended FC level go up drastically. Its recommended not to go over 100, and at that point FC neds to be 11-13ppm. If your doing test strips and your CYA is 100,200,300( which happens easily.) the recommended FC on a strip is 4-5 not in the 10-20ppm range so you get chlorine lock and you get algea and cloudy pools.

So why does the FC go up as CYA goes up? CYA binds to FC to protect it and slows down kill time for bacteria. For a minimum FC should be 7.5% of CYA. If you want to read a great explaination on the chemistry involved look here.

So why am i writing all this? I just went on vacation and my Stenner and 5 gallon bucket of 10% bleach with my 50-60 CYA would only last 4 days. I decided to augment the FC with some 3" tabs from wallyworld. I ran for a week or so just to get the injection and pucks down to last 10 days, and I went through 20 tabs. When I went to look at my chemicals when i got back my CYA was at 90! Yikes!

So its really important to understand that chlorine tabs also add CYA to the water. Lots of CYA. So does shock you dump in when your pool goes green. It will take no time at all between using tabs and shock to fix algea from the high CYA. The pool store will never tell you this they just give you chemicals to fix your issues thats loaded with CYA.

I had to almost replace all of my water again my estimate the CYA was 4-500 given the amount of replacement. And 20 3" tabs raised it 20-30 ppm in 2 weeks is crazy so be aware of this.
 

Dtkokay

Well-known member
Dec 31, 2019
303
Houston, Texas
Your story essentially mimics almost every new person who comes on this forum and asks for help. "The pool store said my chlorine level is fine but my water is cloudy and/or green." Even worse, people buy a lot of unnecessary chemicals recommended by the pool store that do not help. High CYA is the #1 cause of water quality issues from what I can tell.

My area has a Facebook pool owners page, and I've given up on trying to advise people who complain about algae problems because they want the quick fix solution and don't listen. You can't help people who aren't willing to help themselves and aren't willing to spend a little time to educate themselves.

Glad to hear you have been able to get your pool under control, although sounds like you may need to drain some water to get your CYA level back down. At least you know what to do, unless most folks.
 
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miwitte

Well-known member
Sep 4, 2015
105
Charlotte,NC
I just wanted to let folks know how much CYA 20 pucks added i was quite shocked. and ive been having to add water due to the heat and some leaks(thats another post coming up) so it will come down eventually. Stenner, 5 gallon bucket inside of a 30 gallon tote now issues for 4 years now. CYA is super important to keep in check.