We just bought a house with a 26-27k gallon inground vinyl pool so this is my first time maintaining one. I did a lot of reading over at the thepoolforum and here. Luckily the pool was well maintained and looked clear when i pulled the winter cover in April. I almost got pool stored and was training to get levels up using test strips, and then a poor 5 test kit. I was trying to base chlorine off of color matching, got my alkalinity too high, and then dropped to almost no FC. I got a full algea bloom across the whole pool. It was a thin green layer that kept coming back and I needed to change my DE 3 times. My FC had dropped to 1.4 but luckily my CYA was only at 35 before i used any more shock bags and about 40 after my pucks dissolved in the cholorinator.
Now I have my alkalinity down to 100, CYA around 40, temperature is 80, Hardness 280. I've been trying to add enough borates to get to 50 ppm and am about 10 boxes away using the slow method. I had dropped my PH to somewhere between 7.0 and 7.2 (or so I thought as I really hate color tests), added 2 more boxes of borax, and now i swear i'm high 7's. I was fine with the low PH as I read it helps fight algae, but then i read once you have cya, it doesn't matter so added the borax as i've read it also helps prevent algae. 3 weeks ago I hit my slam levels of 16ppm of FC, and maintained between 10-16 since. I have some days that end up being really busy and there is not a timer on the pool pump yet so it can get neglected, and the chlorine levels get neglected. because of this and the terrible strips, i had that first bad algae bloom 3 weeks ago. I still have some late days, but either i or the girlfriend turn the pump on, but I can't scrub everyday. The frustrating part is I thought I was rid of the algea, but now it is blooming and entirely different. Instead of a thin layer it is now dark green patches that look like moss or mold. The cover was left on for 2 days with the pump run and I uncovered it yesterday to find lots of these thick algea blooms and this gray slimey dust bunny looking clumps at the bottom. I am also getting sand in the bottom as they had pavers which were not maintained that I was trying to fix but it has rained several times. Yesterday I shocked to 20ppm FC and scrubbed and ran the vaccuum. This algae seems entirely different than the first bloom though as it is isolated and the water is crystal clear. I got all the gray gunk and algea brushed vacuumed or scooped out yesterday when I did the shock. I left the cover off overnight. I checked today after work and there were those same dark green isolated algea splotches. I again brushed and vacuumed and have left the pump running. My FC had dropped to 15, so I shocked again and this time i'm at 23ppm. I'm leaving the pump run all night this time. I think one of the problems is this inground pool did not have built in stairs, and so they had wedding cake vinyl stairs which are getting algae on them (I had it gone once but its come back and inside the part where you have to put rocks to weigh it down). I actually stuck a puck in there and squeeze bleach out directly in here to try to combat this. Everytime I check my Combined Chlorine it is between 0 and .5. I would think if i'm fighting chlorine I would see a raised CC, but its never been higher than .5. Am i fighting mustard algae here? I can't think of anything else as the normal algea should not have survived my almost 3 week slam (even though I wasn't at 16 the whole time i was always above 10). It is also odd my pressure on my pump has not spiked like it did with the thing layer of full covering algae. I'm aslo wondering what the gray sludge was? Is it possible it was dead algae that had been killed by the FC over the 2 days and just clumping in the deep end? Should I pull out the vinyl stairs, and what can i do to clean them? I do get a good amount of pollen and debris in the pool as it sits in a valley in the backyard at basement level. Can I do something else here like add an algecide or something? The first picture is a kind of close up of the green algea clumps that are now growing, and the second is these clumps on a different day next to the gray sludge puffball. I do get lots of dead caterpillars and slugs in the pool but don't think that is probably an attributing factor. I'll test my FC loss in the morning as well.