Black Algae

[islandflyer]

Hey Guys - I have black algae. I have just pressure washed the areas, now raised it up to 40FC and plan to keep it like that for 24 hours. Its been high cholorine levels for a bit too, so the rest of the algae is dead.

I also bought some Super Black Algaecide - should I hold the pool at 40 for 24 hours, then bring back down to a normal level before adding black algaecide?

Thanks

Lee

oh...

13500 gal
FC - 14 (pressure washed areas then added 3.5 gallons bleach)
CYA - 70
salt water pool

Thanks!

 

[svenpup]

You should finish a SLAM. There is no magic to 24 hours. You need to maintain the shock FC level until you pass all the criteria including no visible algae. Brush frequently throughout the SLAM.

Return the algaecide. It is not needed.

 

[islandflyer]

Will the SLAM take care of the black algae? Also looks like I need to refinish pool, this is where the big spots are.

I was planning on adding borates once this is under control - but it doesn't look like much is happening, although the pressure washing removed a lot and hoping that will allow the chlorine to kill the ablack algae.

 

[svenpup]

The key to eradicating the black algae is maintaining shock level and frequent brushing.

Check put http://www.troublefreepool.com/content/180-Black-Algae for more information.

Once you get rid of it, you can prevent it from returning by never allowing FC to drop below minimum for your CYA level.

 

[RobbieH]

You are going to have to REALLY brush that algae. In fact, I recommend a steel brush since you have plaster.

Black algae loves rough spots in plaster.

 

[islandflyer]

I spent an hour or so with a pressure washer knocking it out. I should get a steel brush tomorrow too.

Anyone want to fly down stay in my house and refinish the pool?

 

[islandflyer]

I forgot to test last night after adding the bleach to bring the FC up to 40, but did add the amount required to get it to there.

This morning it's back down to 21! That seems like a drastic drop, is that common?

Thanks!

- - - Updated - - -

Also, I am not sure where I got the FC of 40 from for the black algae for 24 hours, I swear I read that on here.

Am I supposed to be aiming for an FC of 40 with a swg and 70 CYA, or just an FC of 28?

 

[svenpup]

A drop like that is indicative that you needed to shock and the FC is doing its job. 28 is your shock level, but 40 is the mustard algae level for CYA 70. If it were me I would keep targeting 40, at least until the demand goes down.

 

[islandflyer]

OK - used the last of my bleach last night (I think the bleach itself may not actually be 10%???) to bring FC up to 16.5, this morning is at 16, less than 0.5 CC. However there's still black algae on the bottom of the pool. Will scrub again today, do I take back up to SLAM levels?

 

[Abigail K]

Yes, with black algae you need to continue the SLAM process.

 

[karmabiker]

Take a look at the black algae how to again. This is not an overnight process.

http://www.troublefreepool.com/content/180-Black-Algae

 

[islandflyer]

thanks guys, keeping it high and its dissipating slowly.