Algae on pool floor?

giant_donut

Bronze Supporter
Mar 16, 2021
86
Austin, TX
Pool Size
20000
Surface
Plaster
Chlorine
Salt Water Generator
I noticed some algae (i think?) on the pool floor. It wouldn't sweep away from the brush but I got the metal pole end to scrape some of it. Just wondering if I should SLAM the pool? The SWG is currently off since the pool temp is low (~51 degrees). I've been maintaining with liquid chlorine and while I was away on vacation used some pucks. I added 1.25 gallons of LC (10%) today after recording the log. Time to SLAM and do OCLT?

FC 2.5 (definitely low) <--- it was 4.0 a few days ago and I had added 32 oz of LC (10%)
CC 0.5
PH 7.6
TA 60
CH 525
CYA 70
Salt 3000
 

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Last edited:
My sinuses up here in DFW tell me that's more likely pollen. Your pool water is likely cold enough to prevent algae - but the air is chock full of dirt and pollen from all the recent winds.
 
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Time to SLAM and do OCLT?
Your choice whether the chicken or the egg comes first. Normally if you see algae, its an automatic fail. But so close to (or in) pollen season, you may have to do an OCLT to prove one way or the other. Some go immediately to SLAM and if they fail the OCLT, the ball is already rolling. If they pass the OCLT then it was a 8 (?) Hour SLAM for good measure. (Which never hurts to start the season BTW (y))

Or OCLT and see if you shoukd SLAM or not.

Going forward, if at anytime you suspect algae, visible or unexplained FC loss, its OCLT time. Don't even come ask. Just do. Then come tell us the results.

'Hey all, stuff was fishy and i failed an OCLT. Its day 2 of SLAM. I GOT this'
Or
'Hey all, stuff was fishy and i passed the OCLT, now what?'
 
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Great thanks! Will do and report back.
Don't get me wrong, come tell us that you're waiting for dark to OCLT if you're bored and need something to keep busy. But don't come ask what you need to do, as you already know. You know ? :)
 
Started OCLT. Current FC reading was 5.5. After adding 160 oz of LC (10%) around 4pm I would have expected FC to go up to ~8.5ppm. Asides from algae eating up the FC, the only other explanation is that the chlorine is a bit degraded since I bought that back in May and it’s been sitting in the garage.

Will report back tomorrow if the free chlorine dips overnight.
 
May and it’s been sitting in the garage.
Its 9 months old, plus however long it sat on the shelf. Exposure to heat at any part of that didnt help either. Lol. But yeah. Always verify you hit your target because otherwise you just don't know where you are at. (y)
Will report back tomorrow if the free chlorine dips
(y)
 
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And just like that, you can now (patiently) wait for the pollen to clear. I had so much every year that I'd go cloudy for a couple weeks, even running 24/7. But you still have to prove it so you know you can relax and wait it out. So little effort to do an OCLT and the piece of mind is priceless.

Vacuum and brush to help it along, run the filter a bunch and clean the cartridges at 25% PSI increases.

Be vigilant to ensure you stay above minimum. Staying 1 or 2 FC above target range will not hurt and adds even more piece of mind.
 
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