More CYA?

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zcmack

Active member
Apr 1, 2021
42
Las Vegas, NV
Hello,

I'm struggling to keep up using my SWG and have been since I had it installed last year. I have a CMP powerclean 540 rated at 40k gallons for my 25k gallon pool and even running it at "boost" mode for 11 hours a day, I can hardly maintain the required amount of FC. Is it out of the ordinary to exceed 70 CYA in my area (Las Vegas)? I've already replaced my control station for the SWG due to a warranty issue. Should I be following up with CMP again or am I just scared to raise my CYA to what my area requires?

I finished a SLAM about two weeks ago and can consistently pass OCLT and the water is clear.
 
zcmack said:
Hello,

I'm struggling to keep up using my SWG and have been since I had it installed last year. I have a CMP powerclean 540 rated at 40k gallons for my 25k gallon pool and even running it at "boost" mode for 11 hours a day, I can hardly maintain the required amount of FC. Is it out of the ordinary to exceed 70 CYA in my area (Las Vegas)? I've already replaced my control station for the SWG due to a warranty issue. Should I be following up with CMP again or am I just scared to raise my CYA to what my area requires?

I finished a SLAM about two weeks ago and can consistently pass OCLT and the water is clear.
Click to expand...
Got some test results to share? The SWG should be able to keep up even if it’s on the small side for that pool size. If you were needing to SLAM, that’s a more likely related item.
 
On poolmath > effects of adding > swg
plugging in your CMP Breeze 540, 100% cell percentage, pump run time 11 hours yields FC 3.4 ppm. In our Las Vegas sun, those settings would barely be keeping up with FC being given up to the sun’s uv rays. You’ll have to run your pump longer even with salt cell at 100%.

Also consider bather load to the equation. Generating FC 3.7 ppm is not enough. What are your test kit readings? How low is your FC getting? Are you using the FC/CYA chart?
 
Bperry said:
Got some test results to share? The SWG should be able to keep up even if it’s on the small side for that pool size. If you were needing to SLAM, that’s a more likely related item.
Click to expand...
Currently:
FC: 5.0
pH: 7.6
TA: 80
CH: 600
CYA: 70
SALT: 4450

Typically I'll adjust with liquid chlorine in the morning to an FC of 5.0 or 7.0. Run the cell for 11 hours (rule of thumb being an hour for every 10 degrees ambient temp) and at dusk I'll be around 3ppm. Sorry this is vague, but I've been experimenting daily and results differ slightly. This is with zero bather load. My end game here is get this sustaining FC so that I can trust my pool when I leave for vacation.

I have been using SWG in pool math but that doesn't factor in the "real" loss to sunlight and clearly my hours per degrees rule of thumb is wrong. @an1vrsy any ideas what I should expect to lose to sunlight during this peak season? I certainly have no problem increasing the pump runtime either, I just have been noticing faster pH climb and so I interpret that to mean I'm generating plenty of chlorine and it is just not staying in the pool. I "plan" to go through about a gallon of muriatic acid a week keeping pH in check per the installer of the SWG (who owns the same one) and right now I'm going through about 1.5 gallons. Not a big deal to buy more, but this makes the idea of going on a vacation concerning as I'd need someone to come add acid while I'm not around.

My reticence to increasing CYA is that I then have to adjust FC higher to have the intended effect and any potential SLAM would require more liquid chlorine, but I know the Mojave is a unique case as far as UV goes.
 
zcmack said:
Currently:
FC: 5.0
pH: 7.6
TA: 80
CH: 600
CYA: 70
SALT: 4450

Typically I'll adjust with liquid chlorine in the morning to an FC of 5.0 or 7.0. Run the cell for 11 hours (rule of thumb being an hour for every 10 degrees ambient temp) and at dusk I'll be around 3ppm. Sorry this is vague, but I've been experimenting daily and results differ slightly. This is with zero bather load. My end game here is get this sustaining FC so that I can trust my pool when I leave for vacation.

I have been using SWG in pool math but that doesn't factor in the "real" loss to sunlight and clearly my hours per degrees rule of thumb is wrong. @an1vrsy any ideas what I should expect to lose to sunlight during this peak season? I certainly have no problem increasing the pump runtime either, I just have been noticing faster pH climb and so I interpret that to mean I'm generating plenty of chlorine and it is just not staying in the pool. I "plan" to go through about a gallon of muriatic acid a week keeping pH in check per the installer of the SWG (who owns the same one) and right now I'm going through about 1.5 gallons. Not a big deal to buy more, but this makes the idea of going on a vacation concerning as I'd need someone to come add acid while I'm not around.

My reticence to increasing CYA is that I then have to adjust FC higher to have the intended effect and any potential SLAM would require more liquid chlorine, but I know the Mojave is a unique case as far as UV goes.
Click to expand...
If your FC is getting down to 3ppm, youde be wise to do an OCLT and make sure you don’t have algae starting. A typical sanitary pool loses 2-4ppm FC per day so if you’re losing more than that so thing may be going on. A SWCG can’t keep up with an algae bloom.
5-7ppm is not enough to start out the day. The FC needs to NEVER fall below the minimum for your CYA level. If it starts at 5ppm and loses 4ppm during the day, you’re left with 1ppm.

If you dose up to 7ppm and end up with 3ppm even with the SWCG on, then there’s something wrong. Either something consuming the chlorine other than sunlight or the machine is not working.
 
Last edited:
My SWCG is set to create 4.2 ppm FC right now. It is keeping up and actually adding a bit with our cloudy weather recently.
 
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We are in the same environment, we might be on opposite sides of town. I live in a single story development so my pool gets sun all day unless I close the cover.

25k gallons, I have an IC60 rated for 60k gallons. CYA 70. Keeping in mind 2 - 4 ppm loss everyday to the sun. I run my IC60 set to 50% for 24 hours. This generates FC 4.8 ppm My FC hovers around 7. I prefer to run hot per se. Rather than at the targets per the FC/CYA chart for SWG.
 
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TFP chart says 70 CYA is on the low side for SWG. I have zero experience with SWG, just pointing this out. Based on this however, seems like you could bump to 80 plus and maybe see less FC loss…???… Experts…???

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I keep my CYA above 70. When it drops below 70, the FC loss jumps to over 5 ppm per day (June through September). When I see that, I add 10 ppm worth of CYA stabilizer.
 
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My CYA of 70 is probably more like a 65 but I round up to 70 per everything else I've read on the forum, just hesitant to raise CYA too much. This time of year I get full sun all day. I appreciate the feedback, I'm thinking I'll try adjusting it slightly upward to a firm 70-75, in addition to running for a few more hours daily and see how things go before reporting back.
 
FYI i bumped my CYA up to "somewhere between 70 and 80" and things seem to be holding much steadier. I am still adding liquid chlorine when I have bather load but had great results (maintained acceptable FC) when I left for ~6 days just by raising my FC with liquid chlorine to just short of slam levels before departure.
 
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