This can't be right

[rdietman]

like watermom says , if you vac to fast it will get stirred up and not totally vacuumed . do you have any new subdivisions going up near you , or farm fields nearby?.my pool does this in the spring when the farmers are workin the fields. dust clouds are a risin and that blows a long ways . you dont see it but it happens . also a new subdivision went up last year with a lot of excavating in the spring and the pool had lots of what you describe. i go in with goggles on and dive with the vac hose in hand , its therapy for me, i look forward to it after work on a hot day. kids and wife think im some kind of nut but it works for me.

[PhantomAndy]

I have and 18x36 IG Vinyl

I have seen this both last year, and the year before. I usually don't get it until mid season (in Kentucky).

I believe you may be seeing Algae of some type. The 'slime or gritty' test will tell you which one for sure.

If shocking and (very very slow) vacuuming won't work - and it's slimy then you may need some algaecide (60% Poly-Oxy-Ethyl-whatever it is - nothing else will do).

Both years that I have had this problem, it was algae, and I was very careful to vacuum very very slowly over all areas that had it, and then shocked the crap out of the pool (several times the first year I had this problem) and it would just come right back.

With my pool (22,000 gallons or so) it takes a whole quart bottle of the Poly-Oxy Algaecide to treat the pool properly (about $20-23 a quart). The slime is gone for the rest of the year.

I always add one quart of the 60% stuff when I close as well - which really helps over the winter.

That's been my experience - and I think $20 or so on the 60% Poly Oxy may very well solve your problem.