Why CYA so high for SWG?

[tredos1]

Hi all,

I'm converting my pool over to SWG this Friday after having enough of dealing with bleach additions every day. I'm wondering why the recommendation is to keep the CYA so high? Increasing CYA is a diminishing return kind of thing after a certain amount in terms of chlorine loss from what I've read with the most gains happening in the 30ppm and then a very slow gain in chlorine loss rate as you increase more. There is a nice graph of data in a paper by Canelli in 1974 showing the trend. So it seems like keeping the CYA in the 30-40 range would be still fine. Is there another reason to bump the CYA so high that I'm missing?

I'm not exactly sure how to edit my signature:

20k gallon in ground, 1.5 year old new plaster, Jandy Variable Speed Plus HP pump, Jandy Pro Series JS100 Sand Filter, Polaris Booster Pump, Polaris 280 Pool Cleaner, FC 3-5, CC 0, pH 7.6-7.8, TA 90 (I know I need to bring this down), CH 300, CYA 30.
I know my CH is a little low, but the CSI is okay so I haven't brought it up more. The pH is hard to keep down so I let the CH stay low.

 

[Jimrahbe]

T,

You can run any CYA you want, that is up to you.. But I can tell you not many SWCG's will be able to keep up with the Texas sun if you run a CYA of 30..

Unless your pool has an auto-cover, your cell will have to run at 100% and most likely 24/7 to generate more chlorine than the sun can burn off.

To edit your pool's signature use... Setting, then Signature.

Your TA is just fine... never adjust TA just to get to a number...

Thanks,

Jim R.

 

[HeyEng]

I installed a SWCG about two weeks ago and I have already noticed that my chlorine consumption is down by 2-3 PPM a day. I attribute this to the increased CYA which in turn keeps the FC from burning off so quickly. I was running CYA around 30-40 non-SWCG but have bumped it to 70 with the SWCG.

 

[Texas Splash]

I installed my SWG back in April and learned very fast around mid-May-June that my CYA was a bit low (50). When you think about it, unlike a large bulk-pour of liquid chlorine once a day, your SWG is producing chlorine gas in smaller amounts off & on across it's scheduled runtime. Even my Circupool manual caught-up with the times and recommended an elevated CYA level.

CYA Chlorine Relationship - Further Reading

www.troublefreepool.com

Water Balance for SWGs

Saltwater pools are becoming more and more popular. We discuss How salt generators work and water balance tips for SWGs to run them.

www.troublefreepool.com

 

[tredos1]

Thanks guys,

The thing that gets me is that the higher the CYA, the more FC you have to run and the more FC you run, the more you burn off since it's a percentage. But the higher CYA reduces that percentage and the whole thing is a complicated function. But if it the net is in the right direction and the SWCG cannot keep up then I guess we have to move that way right? I wanted to run it a little lower in case of SLAM, but seems like there's not really a choice here in the Texas sun?

Tony

 

[Texas Splash]

I wanted to run it a little lower in case of SLAM, but seems like there's not really a choice here in the Texas sun?

Yeah, another big reason why it's important to make sure your pool is 100% algae-free before you do crank up the CYA. Then once the SWG is operating, watch it closely for the first week or so with consistent testing to ensure the FC is maintained. Below is another good (and quick) explanation on the subject.

Different CYA level for Salt vs Regular

Can someone please explain the chemistry or technical reason why more CYA is recommended for SWG pools than for regular chlorine pools? I was in the pool store today looking for a leaf net and asked the guy about it just to make conversation and he said that he had never heard of that. I...

www.troublefreepool.com

 

[Jimrahbe]

Tony,

I have three saltwater pools and I'm almost ashamed that I have never performed a SLAM.. I tend to not answer SLAM questions, just because I have so little SLAM experience.. If you just keep your FC and CYA in the proper relationship, you should never get algae...

Thanks,

Jim R.