Trial and Error with SWCG settings and CYA levels

[harleysilo]

Hi, new pool owner, pools been open a couple weeks and just turned over to me 5 days ago.

Test Results

FC 7.5 Was 11 couple days ago, and 14 couple days before that
CC 0
PH 7.8
TA 70
CH 140
CYA ~38
SALT 2900

So i'm dialing in my SWCG. PB wanted it (from his experience) set at 55%. With my autocover being used while we aren't swimming the pool's heat and chems seem to really be staying in. I've dialed the SWCG down to 20% and as of last night i'm at 7.5.

So My CYA is low, do i have a need to raise it to the recommended 70-80 range? I don't appear to have a problem yet of keeping FC, but again my pool is covered unless being swam in. So maybe it's open 2 hrs a day. Weekends will be different of course, as will Chlorine consumption via bather load.

I know this is going to have to be trial and error on my part and i'm fine with that, I'm just curious if i have a need to get CYA up, given the constant "shade" my pool has.

 

[tphaggerty]

I was concerned about CYA levels when I put my SWG pool in as well. Mucked around for a year or two and finally realized that the SWG just works better with whatever the recommended level of CYA is. In my case, the Aquarite wants 60 to 80. When I keep the CYA levels there, everything is nice. When I tried to keep it lower, it seemed to have a lot more problems.

I think the board consensus (plus the SWG Pool School article) is that SWGs work better with a bit more CYA than non-SWG pools.

 

[bobodaclown]

In your case, if the pool is covered, you could run lower CYA levels, since the water isn't exposed to UV (sunlight) that breaks down the chlorine. You could try it. Test your total chlorine level daily maybe towards the evening and see if the SWCG is maintaining the desired amount, other wise you may need to raise the CYA level.

 

[harleysilo]

I wonder, is there any benefit to lower CYA levels?

 

[JasonLion]

Lower CYA levels make it easier to shock the pool.

 

[harleysilo]

So how often (assuming I get the SWCG dialed in) do I really need to shock the pool. My PB keeps talking about using the super chlorinate feature of the SWG. As I understand it if my chlorine doesn't ever drop I shouldn't have to shock unless I have a huge bather load one weekend or some other event.

 

[bobodaclown]

Correct. I've not had to shock my pool in the past year. SWCG maintains the chlorine level nicely, but have had to add some liquid chlorine after a heavy bather load.