First time ever saw some slight green patches on the bottom

dsharp

Member
May 3, 2010
20
New Orleans, LA
Here's are my numbers and situation:

SWG pool - above ground.

Salt 3100
FC 6.0
CC 0.5
TC 6.5
CYA 55
TA 60
pH 7.65

It was a very hot, sunny week and FC dipped as low as 3.5 one day. It was harder to raise it than I thought it would be since it dipped that low.

I cleaned the cartridge filter today, then I brushed the green stuff so it turned the water a little cloudy around it. But it's mostly still relatively clear. Obviously I need to up the CYA, but don't want to do that if I need to shock it. Upping the CYA should also bring the pH down a bit to its usual 7.5 level.

Should I Shock or up the CYA? If I up the CYA, should I raise the FC even higher? I'm usually around FC 6.0 and CYA 70.

I'm guessing I should probably just let it filter overnight (which I don't usually do), check the water in the morning, and add some CYA if all looks good. Right?
 

JasonLion

TFP Expert
Platinum Supporter
LifeTime Supporter
May 7, 2007
37,880
Silver Spring, MD
You should shock if you have visible algae. If it is just a couple of patches, then one night at shock level plus brushing the pool will usually take care of it, though it might be a bit more than that. Raise CYA after you are done shocking.
 

dsharp

Member
May 3, 2010
20
New Orleans, LA
Oops. I hadn't gotten a response so I went ahead and hit the pool with CYA and upped the chlorine just a bit to 7.5. The green patches returned. Fortunately, I read that it takes up to a week for CYA to get saturated into the water so I shocked it with bleach tonight and turned the SWG on Super Chorinating (the highest chlorine production setting).

Here's my new question. Presuming I've knocked it out with this, won't I be left with a pool with a chlorine level of 25 or so? How do I get it to a swimmable level of chlorine? More importantly, WHAT IS A SWIMMABLE LEVEL? Do I get it there by turning off the SWG and just letting it come down?
 

frustratedpoolmom

TFP Expert
LifeTime Supporter
In The Industry
May 20, 2007
12,177
SWSuburban Chicago, IL
Yes, turn off the SWG until it drops down to normal (you have to turn it off to do an overnight FC loss test which you should do in this instance anyway.)

Anything up to shock level is safe for swimming...
 

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