I think I may be dealing with mustard algae but it's confusing me since my cc level remains negligable. I'm getting a yellow blotchy dust coating on the bottom of my pool. Our pollen season is pretty much over and I'm not seeing any on vehicles in the morning so I don't think it's coming from the trees like earlier in the season and I had the pool clear when the pollen season was over.

A month ago I had the pool clear, it was holding 20ppm Cl overnight with no CC. I kept it there for about 4 days then let it drift down while keeping my SWG at 80% and circulating 8 hrs a day. When the pool gets to 12-15 Cl, it gets a little cloudy and the yellow dust starts settling on the bottom. The pool gets a lot of shade and some sun. Even with the water clouding and dust on the bottom, the CC tests O and sometimes .5. I've tried daily vacumming, brushing often, and clean the cartridge often but it doesn't go away, just kind of stays at a low level.

So, I decided to give the shocking another go and treat it like mustard algae. Last night I ran the Cl up to 25, turned off the swg for the night, and brushed the pool. This morning the Cl is 24, CC is 0-.5 and the yellow dust is a gray/blue color. So, my plan is keep the Cl at 25, brush daily, vacuum and clean filter every 2 days, SWG back on at 60% and run the pump 24/7. After a couple of days of this, I'll increase the Cl to 35 for a couple of days and let it drift back down if the CC stays at 0 and the water looks good. Does this sound reasonable, or should I use some Polyquat along the way for maintenance since it's been such a pain so far? I also think I was fighting it last year but not as bad.

One problem that I see for persistence and a return of the problem is that I have in floor cleaning and I've pulled a few of the heads that were broke. There is a light brownish deposit on the parts under the floor, from years of accumulations, it is not slimy. So, I'm sure that the pipes to the heads can have algae growing on these deposits, and there is no way to brush them to break it down.



Oh almost forgot, cya is 50-55, Ph reads high but with high Cl it's hard to put faith in the value, alk is high at 135 or so, CH is high at 500. I'm also working at changing out my pump and a larger filter but would like to clear the water up first.

Thanks for any suggestions for changes to what I'm doing to combat this or how to keep things at bay once it's gone. I'd like to not keep the Cl at 15-20 to keep the water clear.

Sorry this is a bit verbose, too much coffee this morning I guess!