(18,000 freeform in-ground plaster, Pentair Triton II sand filer, Jandy pump and SWG, all about 6yrs old except I replaced the salt cell last summer. Just added borax to 50 to help the PH drift)
Hi everyone! I've been a BBB convert since about 2 years ago when I discovered this website with a new (to me) pool, and you all helped me through the chemistry. Thanks to you, I've had a clear sparkly pool for 2 years with zero pool store additions! Yay! Except...
I'm in Louisiana so we don't "close" pools for the winter. My pump/SWG runs its normal 8 hrs/day/winter except if the water temp gets below 42 it automatically turns on and runs until the water warms a bit. Keeps things from freezing. Seldom does this happen; we just don't get that cold very often. Pump and in-pool Legend vacuum are on timers so no work to do there, 1 hour automatic daily vacuum. I don't have a heater so no swimming from about October til late April when it heats back up. (Admission coming up) Sooo, during the winter I didn't check things as often since, well, it was winter and everything is on timers, just checked chlorine occasionally keeping it around 5 for CYA of 65, and adding MA when needed. Cleared baskets around weekly. Didn't brush much ,and SWG was dialed down for less sun but kept up with the 5 CL just fine. Pool sparkled all winter.
The problem: Last summer I noticed some "sand" on my built-in steps and on a ledge, mostly around the elbows. Swept it off almost daily, it would be back the next day. I have flagstone around the pool and thought it was getting grit in thru rain, etc. Really mostly just ignoring it. Water temp can exceed 100F in summer (ya, it's hot!) The sand persisted all winter. Ignored it, swept it off occasionally. As I started swimming again in May, I started paying more attention to it. Finally a couple weeks ago I "captured" some in a mason jar, based on some reading here, and let it settle. It is not sand. Fine yellowish dust. I nuked it with bleach in the jar but couldn't really tell a difference. It brushes to a poof into the rest of the pool, but the next day it's back on the steps. Did not poof when I brushed the bottom. Since it persisted all winter, not pollen.
I started a SLAM last week after balancing TA (a little low at 50, moved up to 70ish) and pH. CYA I rebalanced about 65. Will take to 70 after SLAM. CH is 330. CC has been zero all winter and still is. During the SLAM I have maintained zero CC so I thought I was barking up the wrong tree, but I've since read threads that MA may not impact CC like typical algae does. I'm on day 4 of the SLAM and MIRACLE OF MIRACLES there is no buildup of MA on the stairs or ledge, for the first time since last summer! However, there is still a slight poof when I brush the stairs, and now there is slight poofing on the pool bottom and I can see the MA slightly move along when I brush the bottom.
My questions: am I killing this stuff? Is the fact that the stairs are now clear a good sign, even though I can now "see" it when I brush the bottom? Am I now brushing the dead algae off the bottom, and that's why it's there now? I also deep cleaned my filter with partial success (that's another thread) and I have some celluose to use if that would be helpful (never used it before).
How will I know when to stop SLAMming? My chlorine holds all night, and no CC. Drops during the day since I have the SWG turned off during SLAM (water temp is low-mid nineties, full sun, outside temps in the 90's). Pool is clear yet still poofs when brushing (minor poofs, no buildup). I'm thinking I slam another day, then go all MA SLAM on it for 24 hours, then drift back to normal, turn on the SWG, and see what happens. Thoughts? Am I doing this right?