Hi, Tom,

Thanks for the follow-up. That's a very interesting comment about your vinyl liner.

It won't come off with a stiff poly brush, but will come off with some gentle wipes with a 'green' pad.
I'm not positive, but I don't think that's algae. When I review your first post, I see this:

but the problem is just like some other posters, the fine algae is going through the sand filter.

That leaves a milky-white pool which I've been vaccuming every day and haven't seen the bottom of for 2 weeks
Combining those two observations makes me think that something precipitated out of your water and has scaled on the vinyl.....perhaps calcium.

To my knowledge, algae dead or alive doesn't create a scaling condition. Nor does dead algae turn a pool milky white (to my knowledge)...more like cloudy grayish blue.

Well, if your water looks nice, that may be enough. I believe I would look at my test numbers very carefully....I think there was something else going on. Have you done a complete test this Spring?