Cloudy pool - SLAM?

[Cbarber623]

I’ve been in good control of the pool all Summer I feel. Had gotten into a pretty good rhythm with weekly testing and cleaning. This week, there was a good bit more debris in the pool, including what appeared like algae. When I brushed, it certainly produced clouds. I’m preparing to SLAM. I’m just not sure what I did wrong to get here? I thought with the level of chlorine I’ve kept, I wouldn’t get algae. Thanks for any advice on preventing in future.

 

[gingrbredman]

It would appear from your pool math logs, your chlorine has been in the range of your CYA, so normally would not expect to see algae. The next step would be to do an overnight chlorine loss test to see what the loss is overnight.

 

[Cbarber623]

It would appear from your pool math logs, your chlorine has been in the range of your CYA, so normally would not expect to see algae. The next step would be to do an overnight chlorine loss test to see what the loss is overnight.

I wanted to last night but we were getting heavy rains so I didn’t think I’d get an accurate test. I just went and bought 14 gallons of bleach. I’m going to go ahead and slam it

 

[Cbarber623]

Could my backwashing, or lack of, be the issue? I read that I did not need to backwash until filter pressure rose 20%. My clean filter pressure is 23. I’ve never had my gauge go to 20% over this. I normally just backwash around every 30 days, but decided to wait it out this time. Until I backwashed today, it had been 3 months. My filter pressure was around 25-26 today.

 

[Mdragger88]

I see that about 3 months ago you had a fc dip below minimum.
It’s possible that allowed something grow in a hidden less circulated place (like a light niche, drain cover or water feature) but your swg & current higher level of fc has been keeping it slightly at bay. Have you noticed increased fc demand?
The Overnight Chlorine Loss Test will tell the tale.
Be sure to check & scrub any nooks & crannies where algae may hide.