Running at Higher CYA Level with Intense Sunlight

[Bill in SoCal]

Been following the TroubleFreePool methodology for a few months now with fairly good results (first time pool owner and still learning.....). The issue I seem to be experiencing is my pool's inability to "hold" chlorine. In the early evening, I add enough chlorine (10% liquid) to adjust the pool to approx. 5 ppm. By the same time the next day I'm testing (using OTO) at 1-2 ppm. I even double check the OTO using two different testing kits, the TF-100 (Taylor) and my Poolmaster. Both match up. When I have tested the CYA a few times over the past month or so, it consistently measures at approx. 40 ppm. Now from what I understand, an "ideal" range for CYA is 30-50 ppm. That's based upon what I've learned from TFP and other resources.

I know that sunlight breaks down chlorine. How quickly I do NOT know (though I suspect somewhat rapidly.....). I live in an area near Los Angeles called the San Gabriel Valley and it gets quite hot here. Also, my pool is situated such that it gets full, intense sun virtually from sun-up to sun-down. No shade to speak off. Also I do not have it covered. When I bought the house the previous owner had a bubble blanket cover for the pool. The blanket was cut into 3 different pieces to match the free-form. I got rid of it for three reasons: (1) It appeared to be old and discolored, (2) it was a pain (due to the size of the pool) to install, remove and store, and (3) the previous owner had cut it to match the outlines of the pool, but he'd cut it UPSIDE DOWN, with the bubbles facing up (instead of down as they should be). So, currently no cover. I guess my question to the TFP community is this:

Due to the heat and intense sunlight my pool gets, would it make sense to run my CYA at a higher level, say 70-80 ppm (or higher?), in order to help the pool "hold" it's chlorine and not burn it off so quick?

I bought some CYA granules and have enough (based upon manufacturer's recommendations) to raise the CYA 30-40 ppm if I want to. If I do raise it, I will likely just gradually add the suggested amount into the skimmer. Run pump 24-48 hours and not backwash DE filter. All of my other chemical numbers seem to be in good ranges. I have NOT (as of yet) added any borates to the pool, though I plan on doing that in the near future as time and budget permits. I appreciate any input or advice fellow community members can provide.

 

[Smykowski]

I would definitely try raising CYA, but do it slowly. Try 50. Then try 60. Don't immediately jump to 80. You know the deal....easy to add, hard to remove. There seems to be a CYA tipping point for every pool, where once you hit it, the FC sticks. I've found that my pool really likes 60.

The other issue I see is that you're letting your FC get too low, so you may have a minor bloom starting. Make sure that you add enough bleach so you always stay above the minimum. You may want to run it on the high side for a couple of days and do an OCLT to rule out anything in the pool.

 

[Richard320]

If you take CYA up to 60, you'll need to maintain FC between 5 and 9. That puts you out of the OTO test range.
If you take CYA up to 70, you'll need to maintain FC even higher. When FC gets above 10, the pH test starts reading artificially high. Which isn't a huge problem if you test before you dose it with bleach, but you should be aware of it.
If you go any higher, and you develop algae, then you're looking at HUGE amounts of bleach to get ahead of it, or a partial drain to lower CYA to a reasonable level.

I run mine around 45-50 CYA.

 

[loop_pea]

Based on what you say, you are only losing 3-4ppm of chlorine a day. That doesn't sound so much for a pool in full sunlight all day, but maybe it can be reduced.

If you decide to increase your CYA, there's no need to go the whole hog. Try CYA at 50 and see how much difference that makes. You can't easily take CYA back out and lower is better if you ever end up needing to SLAM the pool. You could alway try moving up to 60 or 70 later.

Don't forget to adjust your chlorine levels to suit your new CYA level.

A bubble cover will only cut chlorine consumption if the cover is opaque to sunlight (mine is and that definitely helps on days when the pool is not being used).

 

[Bill in SoCal]

Thanks all for your replies. Yes I am starting to see a minor algae bloom. I think it is due not only to the low FC I am able to maintain but also my own laziness! I haven't brushed the pool in a few weeks, since early July. Plan on doing that today and slamming the pool. I will adjust the CYA upwards in 10 ppm increments and see at what point my CL burn rate decreases to a more manageable level. I'm glad I fired the pool guy and am doing this all myself, but it is frustrating being a new(ish) pool owner and new TFP methodology follower and seeing that algae continue to rear it's ugly head!! In time I'll get it all down pat and not look back!! The information I have gotten from TFP community and the confidence it has given me is priceless. Plus the $$$ saved hasn't hurt! Someday I hope to be able to help other pool owners solve their pool problems like the TFP community members have helped me.

 

[wjr75]

I keep my pool with a 45ish CYA at FC 8ppm when I add 12.5% chlorine. I never let it drop below 4ppm.