Green Water - Algae?

[PoolDoc]

There is another possibility. If the tablets had copper in them, copper can stain filters bluish green, and sometimes color the water. If you post a picture -- just supply the link -- to Flickr, Facebook, Webshots, whatever, I can probably tell the difference between algae and something else. If you use Facebook or some similar services remember to make the picture visible to the "world".

[donovan.lambright]

Here's the link. Took this a couple of hours ago.

[PoolDoc]

DEFINITELY, algae!

Add 2 gallons of 8.25% bleach, tonight if possible.

Get cheap OTO kit and test chlorine following night. If OTO light yellow, add 2 more gallons; medium yellow, 1 gallon, DARK yellow to ORANGE, 1/2 gallon.

Continue dosing nightly until pool has no green!

[donovan.lambright]

Add 2 gallons of 8.25% bleach, tonight if possible.

Done.

Still at a loss to understand what happened. I have the Taylor K-2006 kit and have been testing daily (sometimes twice a day). I'm pretty certain that I've been doing the FC, CC, and CYA tests properly but I can't think of any other explanation for how algae could have started when I've maintained (or so I thought) pretty high chlorine levels all summer.

[PoolDoc]

It looks like mustard algae. On some pools, it seems to take root almost instantly, if you let chlorine levels drop. Once present, it doesn't die unless levels are VERY high.

It's difficult to eliminate, but fairly easy to control on vinyl pools -- moderately high chlorine plus careful brushing will eliminate 99% of it quickly. BUT . . . it's not gone, and will return at the first opportunity.

It only lives where nothing disturbs the surface it's on -- thus, it often begins on the side walls in the deep end.

[donovan.lambright]

Makes sense.

As I think about it more, there was one day I let it drop to 3 ppm FC. With the CYA where it is (45), I suspect that's when it started. Grrr. I thought was going to have a trouble free summer.

But the good news is that the water was pretty clear this morning with a heavy yellowish layer on the bottom. I vacuumed it and swapped filters. It's green and cloudy again now, but that's just because my vacuuming stirred it up again. I'll let it settle down with the filter running and will vacuum again tomorrow. I'll hit it with another gallon of bleach tonight.

In one of your last posts, you recommended I get a cheap OTO kit. With the Taylor kit I already have, I wondered why. To keep me from using up all the expensive regent measuring the shock-level FC? Not a big deal; just trying to glean as much info as I can from this experience.

Anyway, thanks for everything.

[PoolDoc]

Yeah, an OTO kit allows you get a quick and dirty but reliable measure of your chlorine level. On my to-do list is to publish an extended color match on OTO, up to 50 ppm.

I'm going to be tied up, and mostly away from the forum for the next few days. But numerous people have reported that borate levels > 60 ppm have reduced their pools 'twitchiness', with respect to algae. If you want to look at that, I'll help you next week. On a pool your size, the cost would be negligible.

[donovan.lambright]

Sounds good. Thanks again!