I posted a while back about what I thought was pollen in the pool. I am having to vacuum to waste nearly every week to keep it away which is **** on chemicals and water bill. This didn't start happening till a month ago, never had this problem last year except once. It looks like a brownish/yellow dust that evenly coats the whole pool bottom. If you leave it for a while it accumulates in seams and around the edged of the bottom of the deep end. I've tried repeated brushing, it just clouds up then re-settles. Filter socks make it about 2 days before they are clogged. I added DE to bump up 2 (13) PSI, after brushing once the pressure climbed another 5-6 (18) PSI then the following day dropped back to 15 PSI. I let it go and my floor was covered again a week later. 10 minutes ago I just vacuumed to waste. put in 6 cups of DE and filter socks.

Numbers are

FC 3.5
CC 0
TA 60
pH 7.4
CH 110
CYA 50 (i'm bringing it up)
Borates probably 30 after the dilution
OCLT .5ppm (once it was 1 but repeated with deeper sample and it was .5) never greater than 1

I believe I do have a small suction side leak as I occasionally get bubbles from the 1st 2 returns but that has been for months and I don't seem to have a water leak.

So... is it crazy pollen season and I'm screwed, is my filter shot (sand is 2 years old), or what. I am about to buy the "enzyme treatment" the pool store wants to sell me, I'm that desperate. Any ideas???

I just shocked to pool to try it. I did notice that when I added 6 cups of DE my pressure bumped up by 1 but is now back down to where I started. I don't see andy clouds of DE coming out of the returns but could I have a filter problem.

If it just thins and out and keeps coming back.........you just might have mustard algae. It sure fooled me into thinking it was pollen. Wasn't slick, none on the sides of the pool, wouldn't filter out when stirred up, DE caught precious little.
Shocking for mustard was the solution.

I'm not sure what the problem is, but I no longer think the over night chlorine loss test can be relied on to indicate the presence or absence of algae. See this thread: over-nite-chlorine-loss-test-failed-me-t36580.html. The appearance of dirty brown/yellowish collections of "stuff" on the bottom might be algae. It was in my case.

On the plus side I just realized the bubbles in my return were from the SWG. I turned it off after I added 3Gal of 12% and the bubbles went away.

I'm going to try to shock it and see what happens. I'm just worried I have a cracked lateral or something else wrong with the filter. When I added the DE the pressure went up to 12 where it stayed for an hour, now it's 15 and if true to form will be back down to 12 tomorrow.

I'll do an OCLT tonight and see what happens. If that's not reliable wow do I know when to quit shocking

@stev32K my water is crystal clear if no one disturbs the pool. It's only cloudy if you stir it up

I positively absolutely guarantee you mine was passing the OCLT! I still shocked it for normal algae TWICE 10 days apart to no good end. Shocking it for MUSTARD levels cured it.

What I experienced was at FC levels of 4 - 7 there was no overnight chlorine loss (four different tests). As soon as I raised the FC to mustard shock levels of 24+ the OCLT was 5 to 7 ppm for six days.

Leslie's sells sucky bleach. I usually buy it form the local pool store at anywhere for 12-15%. This stuff from leslies says 10.5 % and is more like 6-7. Just had to add 2.5 gal more. I wish the other store was open on weekends. Either way its still cheaper than wallyworld

update if anyone is still following. I was mustard algae. Last night FC 36.5 CC 0, this morning FC 33.5 CC .5, this evening FC 26.5 CC 1.

First time I've ever had a CC of 1. Water looks great. Just put in some bleach to bring the FC up to around 40 and will check the OCLT again.

If it's yellow/mustard algae, then be sure to check behind light niches or under removable ladders and put in any equipment you use into the pool. You want to thoroughly kill it all off so that it doesn't return.