Black Algae

Sotex said:

PoolStored,

I'm dealing with this now and did for most of last Summer. It's a pain and I'm very tempted to try Suncoast's Super Black Algaecide. I keep reading on here to not use algaecides, but my wife and I are so frustrated. I travel a lot and it's hard to stay on top of it.

Talk me off the cliff of using algaecides!

I'll run tests for all chemicals later today and report back here. I need a detailed plan to get rid of this and keep it gone!!!

Click to expand...

You can use that algaecide as long as you are ok with adding copper to the water, which will eventually build up enough to cause ugly staining on the pool surfaces and turn blond hair green (maybe that doesn’t matter to some familes…) It’s also quite expensive for what it is and if you aren’t maintaining the chlorine per the FC/CYA chart (which will let algae grow ), you’ll need to keep adding it regularly, which will build up the copper levels even more. Do a search for “copper staining in pool” for what that looks like.

That’s why it’s recommended to just maintain the right FC level instead of the algaecide .

Pictures?

Sotex said:

Talk me off the cliff of using algaecides!

I'll run tests for all chemicals later today and report back here. I need a detailed plan to get rid of this and keep it gone!!!

Click to expand...

Post pics.

Simple answer: algaecide will not solve your problem. Depending on the algaecide, it may make your situation worse.

Black algae is a result of chronic under chlorination...as can be seen in your pool math logs. There is no EASY solution...unfortunately.

Pick at the black algae spots with some sort of physical method: wooden stick, wire brush, or, my personal favorite, weak pressure washer. Then, apply the strongest LC to those spots: pump sprayer, dump jug over the spot—more than once is better. Then run FC hot at 20% of CYA level.

You have to disrupt the black algae. If you have less than ten spots, use a bamboo BBQ skewer. If you have more, a weak pressure wash will make quick work of it (use weak pressure, and use a very wide tip, 40-50 degree, and start far away from the algae (like 18") and move in slowly). Get in the pool with a mask and snorkel and have at it. Some do not like the wire brush method and think it is too aggressive.

Then, apply the strongest liquid chlorine to those spots. Either dump it and let it flow over, or get a pump sprayer. Some have gotten lazier over the years and just dump. It uses more chlorine, but you probably need to raise your level anyway.

Run your FC at 20% of CYA for at least several weeks.

This is the part that sucks; run your FC on the high side in the future at a minimum of 15% of CYA for the life of the plaster.

Post some pictures so we can see what we are dealing with before you attack it. Hate to have you have a different problem...

Hard to tell.

Can you scrape any off?

Black algae is a type of black bacteria.

You should be able to scrape off some and examine it.

It should be a blue-green color.

It is a type of cyanobacteria.

Cyan mean blue or blue green color.

Note that black algae can be toxic and you should take precautions to avoid direct exposure.

Pick at it with a bamboo skewer (or the like), then wipe it on a paper towel. Post a picture of the paper towel.