A MAJOR problem

[PoolDoc]

-- Guys, executive privilege here! I'm taking some of the discussion off-line for reasons I'm not going to explain generally. --
-- So, this is not a precedent setting response NOR the place to debate with me about whether I'm giving the best answer. --

In your case, go with #3.

If possible, you do NOT want to add chemicals without removing the bulk of the algae (#1). And, as you already seem to know, removing algae with a DE filter is a pain.

What you may want to consider, after you've vacuumed the bulk of the chems, is adding 2 - 3 gallons of 30% hydrogen peroxide per 10,000 gallons of pool water. H2O2 is about as side-effect-free chemical as you can use, and SOMETIMES is very effective at killing algae and/or making it filterable and skimmable. If you can't find it locally,you can buy it as Baquacil or Softswim shock at places like
Hydropool
or
SpaandPoolStore

Afterwards, you can start with the bleach and DE. It will help you, if you already have a K2006 DPD-FAS testkit (see Amazon links in my sig) by then, so you can manage high level of chlorine. However you should go ahead and get your pool water tested, to see if there's any stabilizer left, and to check the pH.

Ben

[SL Dan]

Thanks for this and for the other info. I have to say this:

http://www.poolsolutions.com/gd/does...ill-algae.html

is amazing. But I don't quite understand what was done here. Lots of bleach and running the filter too? That seems almost too easy.

[PoolDoc]

So, you want harder??

(Yes, bleach plus filtration did that. It's a typical result for algae on a pool with ADEQUATE filtration, which means no AG sized sand filters.)

[SL Dan]

The photo thread doesn't say how much bleach was used, or how long the filtration was run - but it seems like if I'm willing to clean the filter, that might be the least wasteful method. As mentioned, I have a DE filter. My neighbor does his own pool work. I've been encouraging him to look at this site, so I have to show him those images. Its really impressive.

BTW, Costco advertises 6% Clorox @ $12.99 for a case of 6 96 oz. jugs.