CYA Usage

[swirlywater]

I have virtually no CYA in the water; can't really test less than 30ppm. I use a tri-chlor feeder all season. Last year my pool builder told me to never add CYA because I use tri-chlor. By the time I closed the pool, I think i might have had 30ppm in the water, then I lowered the level for the winter. At this time it would appear I have no CYA in my water and I can't get Chlorine to stay in the water. Is it safe to add stabilizer to get my CYA up to 30 and use tri-chlor all summer?

 

[JasonLion]

CYA sometimes disappears over the winter. Sometimes that is accompanied by there being ammonia in the water in the spring, and sometimes not. Ammonia can prevent you from maintaining an FC level regardless of the CYA level. Low CYA levels will cause chlorine to vanish as quickly as it is added during the day, but not at night. Ammonia will cause chlorine to vanish instantly at any time of day.

If you plan to continue using trichlor, you only want to add about 15 ppm of cyanuric acid. That should be enough to get you over the current issue (assuming no ammonia) and not so much that you make your CYA problems later in the season any worse than they need to be.

By the by, we don't recommend using trichlor tablets because CYA will accumulate to unacceptable levels before the end of the season.

 

[tim5055]

Is it safe, yes. But, as you are aware the tri-chlor adds more. Just don't follow the normal pool store advise of always having your FC at 3-5ppm. The more CYA the higher you have to keep the FC. When my CYA was 200 plus my normal FC was around 14 if I recall. CYA is not a bad thing, you just need to understand the relationship between it and chlorine and stay on top of it.

But, as we teach here liquid chlorine doesn't add any CYA.....

I am more concerned with the Nature2 as you are adding metals which at some point may cause staining.

 

[swirlywater]

Is there a test for ammonia? I didn't have a CYA problem last year so I don't anticipate one this year. I test every 2-3 days so if it rises I can switch to bleach, which is what I am trying to use now, but I can't keep it in the pool very long.

- - - Updated - - -

I just took the Nature 2 out of my signature. After reading this forum I decided not to use i this year. I posted the first thread here before I fixed my signature.

 

[ping]

Please post a full set of test results and what test kit you got them from, FC, TA, pH, CH, CYA. How does the water look?

If you have a test kit that has the FAS/DPD chlorine test you can do an OCLT, see my signature for the link, to determine if there is a low organic load consuming the chlorine. A proper test kit is essential in troubleshooting problems with water. It is too early to say if you should bump up the CYA without more information and if you need to SLAM the pool you want to have the CYA in the 20-30 range.

Adding 10-15 ppm of CYA will be fine for now even if you need to SLAM.

 

[JasonLion]

There are ammonia tests, sold for fish tanks. Usually it is simpler to add some chlorine after sunset, and then measure the FC level half an hour later. If it is zero after half an hour in the dark and there is no visible algae then you almost certainly have ammonia.

 

[swirlywater]

The water looks great, and the levels are fine. I have the Taylor K-2005, but just ordered the FAS/DPD test which should arrive tomorrow. FC=~1, CC=0, PH=7.5, TA=110, CH=90, CYA=undetectable. I don't need to SLAM the pool, I just wanted to get the water levels set and filter running before it warms up and algae starts growing. Since the pool won't really be opened for at least another month I don't want to be messing with chlorine everyday.

 

[swirlywater]

I am curious now, where does ammonia come from?

 

[JasonLion]

Ammonia is a side effect of CYA getting broken down by bacteria over the winter. Often the breakdown continues and breaks down the ammonia as well, but not always.

Since you have an FC reading above zero you don't have ammonia. Ammonia reacts very quickly and eliminates any FC before it can be measured.

 

[swirlywater]

Thanks Jason. If I understand right, if that ever becomes a problem it can be eliminated by properly SLAMing?

 

[JasonLion]

Yes, SLAMing will get rid of ammonia. However, even more aggressive treatments are often warranted once ammonia is confirmed.