Green dust on bottom, but water is clear?

Jul 19, 2022
15
CA, USA
Been battling this since Summer began. I have a pool with a 1 foot shallow end that goes down to about 7 feet. It's 40 CYA and I keep chlorine levels at 3-4ppm. The water is clean but the deep end has accrued an accumulation of greenish brown dust on the floor, which makes the whole deep end look murky. I have gone through SLAM and it doesn't do anything for this fine dust. When I do brush/sweep it, it moves around like a cloud, so it is definitely very very fine and obviously the cartridge filter doesn't catch it. When I brush and sweep the shallow end, I do push it into the deep end naturally, so this may not have helped the situation. I tend to find similar stuff clinging to my plaster walls, and some spots are worse than others to get out.

What is it?
Is this dead algae? Mustard algae? If dead, am I just not SLAMing long enough? Is this stuff supposed to completely go away once dead, or is it normal for remnants to just sit there? I hear mustard algae is chlorine resistant, so could that be why I just can't get rid of it?

Vacuuming?
Secondly, if SLAM just won't do it, do I need to buy a manual vacuum? The thing is, I have a cartridge filter with no multiport valve and don't think I have a way to vacuum to waste. Is there anything I can buy to catch the debris before it gets past the skimmer? Should I try vacuuming with a skimmer sock on?

Other ways?
Can I just get a just skimmer sock and hope that I can stir the water up enough that it stays on the surface and hits the skimmer? My thought is that maybe I can try and sweep that dirt into the main drain to force it to go through the system, then catch it on the surface before it settles on the bottom with a skimmer sock. I tend to find greenish brown clinging to the plaster corner near one of the return jets, and the ~ 1 foot shallow end by the edges where the water goes clockwise around the pool- so maybe it is actually circulating through the system rather than stagnantly sitting there 24/7.

Sorry, just lost and have googled/searched TFP for this and really need some direction. Thank you

Pic below:

Screen Shot 2022-07-25 at 12.53.34 PM.png
 
If you are using the test kit in your signature, you never did the SLAM Process

Get a proper test kit, specifically the K1515 kit, and follow the SLAM process.
 
If you are using the test kit in your signature, you never did the SLAM Process

Get a proper test kit, specifically the K1515 kit, and follow the SLAM process.
Fair enough, thank you. So with a proper SLAM this fine powdery cloud-like dirt should be gone? What I am getting it as, a SLAM should kill all algae, but what is this algae like when it is "dead"? Would there not even be green specks leftover?
 
It's 40 CYA and I keep chlorine levels at 3-4ppm
Minimum is 3. Target is 5-7 and everyone is losing their highest amount of daily loss for the season right now. With an average seasonal loss of 2-4 ppm a day, and many seeing 4+ right now, you are under sanitizing your pool and seeing the proof.

Right now, you need to SLAM. (Proper test kit / components needed). After that, always dose daily to lose today's loss and remain in target range tomorrow. It catches throughout the season. If you've been losing 3ppm a day lately, dose to 8+ to end up at 5+ tomorrow. Adjust as needed up or down. If you do, we will never have this conversation again. We can talk about the weather or hobbies instead, but it will NOT be about algae. :)
 
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