Context: bought a house in Ontario, took possession in April. Have been battling the pool since early May, although the first couple of weeks were mostly focused on getting all the hardware working (which it now does). Pool went green (as it tends to when you don't have testing equipment and let the chlorine dip) with the big spike in temperatures in May, and hasn't been restored yet. Notes: new O-ring in the multivalve, new sand in the filter (completely emptied and replaced sand, as it was pretty cruddy). Cleaned out impeller, checked all couplings. I only get ~ 7 PSI when running all 3 outtake returns, and ~ 14 PSI when running only 1 of the 3. I expect the low numbers are because of the low-HP pump.
Equipment: 20x40 pool, 10' deep end (don't know exact volume, need to finish measuring some deep end pieces). 3/4HP Hayward pump, sand filter (unfortunately).
I've been reading lots of threads on this forum, learning and focusing. Before I discovered the forums, I had tried pool supply stores, all of which told me different things, and all of which sold me lovely products which may or may not have helped/harmed (one store was ok-ish, and suggested a decent flocculant to get the sediment out, which sorta-kinda helps/helped).
Things that went into the pool over the last 4 weeks: lots and lots and lots of chlorine. Some pH+/- once I started testing, just to stabilize levels. Flocculant. Stabilizer.
Last week I really got into reading these forums, and bit the bullet and ordered a proper test kit. I'm in Ontario, so it's a giant PITA. I ended up with a Taylor 2005C rather than a 2006, unfortunately, and I'm not sure I want to spend another $120+shipping just to get the FAS-DPD. While I was waiting for the kit to arrive, I did a "guess and pray" SLAM for five days. I balanced the pH to 7.3, raised the FC to >10, and kept it there while the filter and my robot went 24/7. After the kit arrived I tested CYA, and found it to be basically 0, but the SLAM should still have worked because I topped up the chlorine every 2 hours (except at night), testing the FC every time to make sure it stayed high. Overnight during these 5 days the FC would stay above 10 -- it was likely dropping somewhat, but it never dropped below 10 overnight. At the end of this process, when I turn off the filter & pump, and leave it alone for a few hours, the water goes clear with brown cloudy sludge at the bottom (probably from residual flocculant precipitating stuff out). You can see pictures of what this looks like below, from last night. However, if I vacuum at the sludge, half the cloud goes back into the water, and then the pool is non-blue and cloudy again. Rinse, repeat, over and over. It's gone down significantly over time (the total volume of brown sludge), but overnight some always reappears.
Pictures of the pool from last night:
My readings last night (when the kit arrived):
CYA: ~ 0
Since the CYA was low, I took 200g of stablizer and put it in a sock and left it in front of the return jet with the pump on overnight. This morning I squeezed it and finished putting the CYA into the water. I'll test it tonight to see what levels it's started rising to, and keep testing for the next 72 hours until I know whether or not I've gotten it up to >30.
I've been keeping the FC high through yesterday and today, with the filter running, and it might be a little bit clearer now than it was two days ago, but still somewhat green.
Pictures from an hour ago:
So ... advice? Is the cloudy green-shaded particulant just dead algae and crud and I just need to filter and filter and filter until it finally clears up, while keeping FC > 5 and CYA ~= 30? Or is there somehow still algae surviving? I have a decent (Polaris P945) pool robot that scrubs the bottom and sides for me, and I've been manually scrubbing the sides as well. As mentioned, I've been vacuuming quite often, but it's not terribly effective at picking up the brown cloudy stuff from the bottom, because a significant portion just disperses into the water and it all goes cloudy again.
Further note: can't add D.E. to the sand filter, unfortunately, because ... Canada. It appears to be basically impossible to get pool-grade D.E. up here. Along with Taylor kits and all kinds of stuff. Sigh.
My wife is pushing me to "just get a pool company to come", but I can't really see what they'll do, unless they literally bring a giant filter and vacuum the entire pool through a fine-micron filter.