Hi, all. I opened my pool (18k gallons, plaster) this past Saturday to find a very murky green, unlike I've ever seen it before. I decided to try to treat it rather than drain. I adjusted pH to ~7.2 and added stabilizer to get to 25-35 CYA.
When I mentioned the algae to the pool store owner, she recommended starting with some non-chlorine shock so I added 2 lbs of 45% Potassium Monopersulfate on Saturday afternoon. Apart from that, I have been following normal SLAM. It's been about 3 full days now and I have not seen much if any improvement in the water, in color or clarity. The pump has been running 24/7 and pressure is normal. I opened it and cleaned the cartridges once after a couple days, just to make sure that it was filtering properly, and got plenty of algae off, but it was by no means saturated.
The weird thing, though, is that almost no chlorine at all is being consumed. Last night, overnight, it somehow gained 1 part (I assume testing error). These are the most recent readings I recorded, starting yesterday at 12:30p, using a new FAS-DPD test from the TF-100 kit:
Time / FC / Addition oz 12.5%
12:30 / 13.5 / 0
14:15 / 13.5 / 0
16:32 / 13.5 / 0
18:30 / 11 / 41
22:00 / 17 / 0
09:30 / 18 / 0
I didn't write down the previous measurements, but it was sticking right around 13.5 back into the previous day as well. So I have no idea what's going on here. There is no chlorine feeder or any source of chlorine other than the bleach I'm adding. Why is virtually no chlorine being consumed when the pool is still solid green? Why did adding 41oz bleach raise the FC that much (pool calculator said it should raise it by 2.2)? Is that initial non-chlorine shock throwing things off even after 3 days? I would just keep up the SLAM but I'm burning through my FAS-DPD kit just to find no change over and over again. I'd be very grateful for any input.
For an idea of how green we're talking, the step that can be seen in the lower left of the picture is about 20 inches below the surface. (Sorry for the reflections, it's really hard to get a decent picture of this.)
When I mentioned the algae to the pool store owner, she recommended starting with some non-chlorine shock so I added 2 lbs of 45% Potassium Monopersulfate on Saturday afternoon. Apart from that, I have been following normal SLAM. It's been about 3 full days now and I have not seen much if any improvement in the water, in color or clarity. The pump has been running 24/7 and pressure is normal. I opened it and cleaned the cartridges once after a couple days, just to make sure that it was filtering properly, and got plenty of algae off, but it was by no means saturated.
The weird thing, though, is that almost no chlorine at all is being consumed. Last night, overnight, it somehow gained 1 part (I assume testing error). These are the most recent readings I recorded, starting yesterday at 12:30p, using a new FAS-DPD test from the TF-100 kit:
Time / FC / Addition oz 12.5%
12:30 / 13.5 / 0
14:15 / 13.5 / 0
16:32 / 13.5 / 0
18:30 / 11 / 41
22:00 / 17 / 0
09:30 / 18 / 0
I didn't write down the previous measurements, but it was sticking right around 13.5 back into the previous day as well. So I have no idea what's going on here. There is no chlorine feeder or any source of chlorine other than the bleach I'm adding. Why is virtually no chlorine being consumed when the pool is still solid green? Why did adding 41oz bleach raise the FC that much (pool calculator said it should raise it by 2.2)? Is that initial non-chlorine shock throwing things off even after 3 days? I would just keep up the SLAM but I'm burning through my FAS-DPD kit just to find no change over and over again. I'd be very grateful for any input.
For an idea of how green we're talking, the step that can be seen in the lower left of the picture is about 20 inches below the surface. (Sorry for the reflections, it's really hard to get a decent picture of this.)
