So another week has passed now and pool is still 99.5% clear (it's super clear and probably acceptable to most people) but not as sparkling clear as I remember it being before the algae started. It's definitely not getting any worse over the past week but hasn't been getting better. I kept checking OCLT every 2 or 3 days and I have no loss over night (and also no extra chlorine loss over during a sunny day compared to what I was used to). At night when I shine a bright flashlight in the water I can see extremely fine particles in the water.
Yesterday I turned the pool pump off early and let the pool water settle for about 15 hours. I looked at the pool this morning and finally and looked crystal clear like I was used to before. However, upon brushing the floor, as suspected there was dust all along the button of the pool that puffed up (you definitely did not notice it laying at the bottom of the pool, but a slight dusty cloud did form when you brushed around). I have a round pool so usually larger debris eventually accumulates in the center of the pool when the pump is turned off, but I did not notice that this happens with this dust, so it must be extremely fine. So after fully brushing, once again the water is back to looking very clear but dull.
So I'm pretty much sure this fine dust is getting through my sand filter and I need another means of getting it out.
Any suggestions? Things I am thinking about is either putting a white sock or thin weave fabric on the skimmer basket to try to catch the dust, adding DE to sand filter (although I have so far been reluctant to do this since I don't want to be dealing with potential DE dust in the pool in addition), letting the water settle for 24hours and vacuum floor to waste, or finally, giving up and using a clarifier product that might clump this stuff together and be captured by the filter.
SLAM process was great in quickly killing off the algae, but dealing with the last bit of extremely fine algae dust to go from super clear to sparkling clear water seems to be a nightmare.
Brief summary timeline of SLAM process:
July 12th - Storm at night - lots of water accumulated in pool.
July 13th PM - came home from work noticed the water has become slightly cloudy and green tinted (still could easily see the bottom). Measured chemicals - chlorine was 4.5ppm at this time, CYA was 30 which is what I have maintained it at, dropped pH a bit down to 7.2, upped my chlorine to 12-14 ppm. Water quite quickly turned from a green tint to a blue-whitish tint.
July 15th - I ended up turning pump off for the night, letting dead algae settle to bottom, and vacuumed floor to waste, this helped out a lot.
July 18th - maintained SLAM levels diligently until here, where water finally became crystal clear to my Wife's eyes, however to my eyes, was super clear but not really as crystal clear as it was before (maybe like 99.5% of the way there). Small fine particles seen with flashlight at night. I have passed OCLT every night since the 14th. We have been diligently brushing every couple hours to keep any dust in suspension to get it to pass through the filter.
July 26th (today) - I have been running chlorine at 8-10ppm ever since - slightly above the max for my CYA, but below SLAM levels. Pool is neither getting any worse or any better, water still very clear but does not have that sparkle it did before. Between July 18th and 26th, I did a few OCLT and each time was no loss in chlorine. Pump was off for 15hours since yesterday evening, and some brown dust can be brushed up from the bottom of the pool.