Black algae outbreak in my pool (Page: Home Depot, school, maintenance)

[gsm113]

My pool floor has started growing dark spots that feel like velvet carpet to the touch. A little googling suggests it's black algae. Is this something our weekly pool maintenance service should have prevented? Should I look for a new pool company?

[Ponderosa]

Don't know that you can blame the pool servicer right off. That's a challenge this time of year because black algae seems to be resistant to normal sanitary chlorine levels. Even shock seems ineffective. The way I have dealt with it is to put a tab right on top of the spot. If it is on a wall you can hang it in a sock or something.

[sargeant79]

I've had a couple situations like this before and the concentrated algaecide they sell at Home Depot for about $15 has taken care of it easily both times. It might be overkill if the rest of the pool is fairly clean, but it won't hurt as long as you make sure the PH in the pool is still maintained in the normal range. At least that was my experience.

[Reedus]

Disagree with Ponderosa. Black algae shows up when chlorine sits below 1ppm for an extended period of time. Your pool company should have caught it before you had an outbreak. It's a #%€* to get rid of. Scrubbing with a wire brush and chlorine puck will get rid of it. Keeping your chlorine level above 5ppm for the next 2 months should keep it from returning

[cactusland]

Disagree as well. Something is off, start throwing in the chlorine.

[AZJoeD]

To answer your question, yes this could have been prevented with proper maintenance. But it is too late now.

Chances are your water needed to be changed. When the Cyanuric Acid level gets too high the effectiveness of the chlorine diminishes. This happens over time especially when you use chlorine tabs that have too much stabilizer. The stabilizer is supposed to aid in chlorine absorption, but when too much is used it has an opposite effect. Then algae takes hold. This is likely what happened to you.

There are chemicals that will solve your problem temporarily, but it will likely come back if you do not clean everything, pool, tile, filter, skimmers, even the tools.

The best long term solution to ensure it does not come back is to drain the pool, clean everything and refill and re-balance the water.

[gsm113]

Thanks for the suggestions. The pool is relatively clean other than the black algae so I hope emptying and refilling isn't necessary.

[LBTRS]

Yes, it was definitely preventable by maintaining the proper chlorine level. Allowing the chlorine to get below 1ppm for too long of period is what allows algae to grow. Who's fault it is depends on who allowed it to get so low.

You don't have to empty and refill a pool due to an algae bloom. Properly treat the algae, water and filer and it will be gone and you'll be able to keep the same water. That is assuming your water is otherwise alright. If you've been using tabs for a long time your CYA may be too high and the water may need changed. Only a proper water test will determine that.

Knock on wood...I've had my pool for 8 years and never once had algae in it. My chlorine level is maintained daily though.

[sh9730]

Pool School - TFP Home Page

Best site I ever found. Took about a week to get things in normal balance using store bought (not pool store) chemicals of Bleach, Borax, and Baking Soda with an occasional CYA added in and a GOOD test kit.

Now I test once a day for chlorine - add about 20 ounces (we have a small pool - would be a bit more for larger) - takes all of 2 minutes and my water is crystal clear! Except for days after dust storms!! ARGGHH...

Total cost less than .50 a day - plus electricity. No tabs, no pool guy.

[froglipz]

Bad pool service! Make them responsible to correct the problem, that is what they have been getting paid for!