The best product I have found is a product called "silver algydine." You MUST follow the instructions on the bottle exactly and it will disappear in about 2 weeks.

Ugh! I had that stuff & it's EVIL! Have you tried scraping/brushing it too? I didn't try any ofthe products listed. I scrubbed the heck out of my pool with a wire bristle, dumped in gallons of bleach. I think at one point I let the water level go down & treated the areas with acid. Don't know if that's recommended & it's not great for your finish, but I knew my pool would be getting reno'd.

Not sure if this is why, buy I think the reason we had it in the first place was b/c we had a leak through the light fixture in the pool & the ground water was seeping back in. We found out when we drained the pool, the drained water in the yard was drizzling back in through the light.

Yes, I've been brushing it 2-3 times a day and it doesn't seem to be helping at all. I'm tempted to take some fine sandpaper and see if that would work - or is that a really bad idea? I had a small stain on my sun shelf last year and it seemed to disappear with a little sandpaper, but this is a pretty big area. I have no idea why I'm getting the black algae, the pool was installed last year and uncovered for the first time May 15th. I didn't really notice anything wrong, and then boom, one day there it was, and it seemed to keep spreading, although with the dose of black algae killer at least the spread seems to have stopped. It's very frustrating b/c nothing seems to be helping it. I will try the silver algydine...and/or sandpaper.

Try the black treat below it works great!!!

Here is a link that might be useful: Black Treat

So sorry Sophie! That stinks. I know the stuff is awful & hard to get rid of. In my case it was annoying, but like I mentioned we needed to re-do the pool any way.

I read some where (maybe the pool forum?) that it can come in from a leak or from swimming in the ocean & then into the pool. I will see if I can't find that info somewhere again. Hope you find a remedy that works soon. You should be enjoying your pool, not scrubbing it!

I recommend you go to TroubleFreePool.com and join and then post your question under the Algae section. Joining the forum is free and there are a lot of professional pool people on that forum, not that there are not good resources here, just that it never hurts to get more input. Ron

When you cover your pool, it's easy to forget to check the chemical levels in the pool. Have you taken a water sample to a pool supply store? My problem was TDS (total dissolved solids) made it too difficult to keep the chemicals in balance and made them less effective. They run several more tests than what is in the standard home kit. I drained the water and used liquid chlorine with a brush. Have to get the roots of the algae - I even used a dental probe/scraper. That was last year. Haven't seen any black algae since.

Try this - put on the snorkling mask and some rubber gloves. Take a chlorine puck and scrub the algae with it.

Black algae is pretty vicious stuff. You might also try a polyquat algaecide, and a really high level of chlorine shock for several days.

Thanks for all the advice. All the chemical levels of my pool are within normal range. I'm going to try some things this weekend and will let you know if anything works.

Does anyone know where I can purchase the "silver algydine" muddyboot recommended? Thanks

Looking for directions for the use of polyquat 60 to help with Black Algae.

What to do before??? PH? Brush? Vacuum? Shock?

How much to use?

How to put it in?

What to do after???

I posted the same on poolforum.com and got no responses

citiguy,
Most algaecides use similar directions for application. They are normally printed on the bottle. Always balance PH prior to treatment. For black algae it's best to use a stainless steel brush to break the membrane and allow algaecide to work properly.
Know your gallonage for proper dosage. Preparation for treatment is about 90% of the work. Sometimes additional treatments are necessary. Good luck.

The directions give the ratios for routing or startup and not much else

What does balance PH mean? I keep the PH 7.4-7.8

Beside the PH and SS brushing, what other prep is needed?

How would you add the algaecide to the pool?

How long to wait before additional treatments?

Tri-Chlor is the ONLY way to get rid of Black algae. I.e.; Chlorine tab (hockey puck) or in a granular form for the bottom of the pool. Put the Tri-Chlor directly on the spot(S) and let it sit. All of the other chemicals, if you look on the back, to treat black algae has the main ingredient of TRI-CHLOR>

Once its removed fill the void it grew in with something like a POOL Putty(two part epoxie).Black alge likes voids to grow in.