After SLAMing pool, guess what? Black algae outbreak

[1LowPool]

So not but two weeks after successfully converting my green lagoon of a pool into a beautiful summer oasis the FC levels had dropped while I was away for work and vacation allowing for this (what appears to be) black algae to take hold.

It seems to have formed in all the classic rough areas of the plaster which is very old and it's spreading like wildfire.

I have read several threads here on the treatment of this particular kind of algae and understand that every case is a little different and requires a little tweaking however the basic method remains the same. Any advice/criticism regarding my plan of attack would be greatly appreciated.

The plan:
1) Raise FC to yellow/mustard algae shock level appropriate to CYA level.
2) Scrub with metal brush entire pool with attention to areas with visible black algae.
3) Maintain levels for 2-3 days while scrubbing trouble areas several times a day.
4) Allow levels to drop to high end (and up to 50% higher) of normal FC levels.
5) Trichlor tablet as necessary for increased efficacy


Chemical levels to follow in next post. As always thanks to the great minds that run this site!
The outbreak:

 

[pooldv]

Have you seen this article in Pool School?
Pool School - Black Algae

 

[1LowPool]

Have you seen this article in Pool School?
Pool School - Black Algae

Hi pooldv!

I have seen the article. The numerous threads that I've also read have senior members who also recommended bringing up the pool to shock levels initially. Would you recommend simply elevating the FC levels?

 

[1LowPool]

So the first test this evening showed that the elevated FC levels from a day ago dropped dramatically after a brushing this morning:

CyA 30
FC 1
CC 0
pH 8.0
CH 280
TA 90

I brought the FC up to 6 and then broke a piece on the filter by accident so I'm off to the store in the morning to replace that so I can keep it running on schedule. I also intend to bring the CyA up to 50 and lower the pH just a touch.

 

[MarianParoo]

I am no expert on that nasty algae thang you got going. But... Why would you want to raise your CYA? It will just take higher amounts of FC to get to your goals?

 

[1LowPool]

I am no expert on that nasty algae thang you got going. But... Why would you want to raise your CYA? It will just take higher amounts of FC to get to your goals?

Hi MarianParoo! Maybe I misunderstood but doesn't that help prevent a lot of the FC from burn off by the sun? Yes it would take more FC initially but the losses from the sun would be mitigated. Is that not the case?

 

[BuckeyeChris]

Your FC level during a SLAM makes most of your FC exposed to the sun, so raising CYA won't really help. It will just use up you FC test drops faster. Once you are back to maintenance mode, and 99% of your FC is protected by the CYA, there are some benefits to being higher.

But for a SLAM, 30 or 40 is ideal.

 

[1LowPool]

Okay, I understand. So the article that pooldv linked states to simply raise FC levels above the high end of the normal range and maintaining that through the summer. Would a SLAM be unnecessary?

 

[pooldv]

If you are only trying to get rid of black algae then no need to SLAM. Just keep FC above target and below shock level for your CYA and brush, a lot. Up to shock level is fine for swimming and killing black algae. Much easier to brush when in the pool.

Yes, I would raise CYA to 50 and lower PH to 7.6 or so.

 

[MarianParoo]

Did you ever do the "smudge" test?

 

[1LowPool]

Thanks pooldv. That's the new plan. I'm scrubbing daily and and keeping the FC levels up with no SLAM. Already seeing some nice improvements!

Hi MarianParoo. I did do the smudge test. It's nasty stuff!

 

[MarianParoo]

Looks horrible!