The breed of algae that came in with spring rains is real tough. It’s so fine it doesn’t get caught in regular filters. WE’ve tried every algae killer in existence.
I finally ordered, from Foster & Smith, some real fine (lime green) filter pads, and they made a little headway.
I decided to use the trim from one to put in the bottom of the pre-filter basket, effectively doubling the filtration in every cycle through the system, and bingo! we can see the rocks in the bottom this morning.
I think I have finally found the answer. I may get some filter felt sheets to sit atop that pad, in the 1 micron variety, and that may get it.