Treating black algae when pool is empty

Tyler80

New member
Apr 26, 2021
4
Las Vegas
Pool Size
25000
Surface
Plaster
Chlorine
Liquid Chlorine
Hey y'all, I'm stoked to have found this community and am reading tons of information. I'm wondering what I should do to treat a moderate black algae problem in my mom's pool. The pool is currently being drained and will be refilled ASAP, but what should I do while the pool is empty to fight the black algae? Pressure wash? Scrub? Acid wash? Chlorine wash? The pool is old but in good shape generally. I plan on taking control over the chemicals and learning the TFP methods once the pool is filled. But what should I do while I have the pool empty if anything? Thanks!!
 

YippeeSkippy

Mod Squad
LifeTime Supporter
Jan 17, 2012
17,389
Evans, Georgia
Please do NOT pressure wash you plaster, you risk damage. Ditto for Acid Wash = loss of plaster.

A good scrub with liquid chlorine diluted 1:1 with water and a good scrub brush is a good idea while empty.


Maddie :flower:
 

Tyler80

New member
Apr 26, 2021
4
Las Vegas
Pool Size
25000
Surface
Plaster
Chlorine
Liquid Chlorine
Thank you Maddie! That sounds appropriate. I definitely did read the black algae guide and am looking forward to future elbow grease.
 

Katodude

Silver Supporter
Aug 22, 2017
1,687
West Palm Beach/Florida
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If you really want to be certain, before you do what Maddie suggests. I would take a bamboo bbq skewer and pick at all the spots. Dig them out well. The scrub them with the brush and chlorine mixture. That way you make sure you get all the way down to the roots.
 

Katodude

Silver Supporter
Aug 22, 2017
1,687
West Palm Beach/Florida
Pool Size
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So it is better than trying to do it when the pool is full, ask me how I know.

The key to black algae is really getting down to the roots and then getting chlorine in to kill that. It has a very protective waxy layer so the more you can break through that the better.

Then and this is the most important part. When you fill back up you will need to run your FC hot. I have a SWG and I use the FC/CYA chart like I am a regular chlorine pool. The ideal is my new minimum. I completely ignore the minimum level that is way too low for me.
 
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Tyler80

New member
Apr 26, 2021
4
Las Vegas
Pool Size
25000
Surface
Plaster
Chlorine
Liquid Chlorine
Right on Kato.. I lightly pressure washed and then scrubbed the Crud out of the black algae with a stainless steel brush while the pool was empty then rained a 50/50 water/chlorine bath over it and scrubbed some more with a scrub brush, then rinsed.. I filled the pool up right after.. I ordered the t-100 pool kit should be here by Thursday hopefully then I'll get the levels up according to the black algae guide.. and then scrub scrub scrub!
 

Melissa Rimer

New member
Apr 28, 2021
2
canada
Right on Kato.. I lightly pressure washed and then scrubbed the Crud out of the black algae with a stainless steel brush while the pool was empty then rained a 50/50 water/chlorine bath over it and scrubbed some more with a scrub brush, then rinsed.. I filled the pool up right after.. I ordered the t-100 pool kit should be here by Thursday hopefully then I'll get the levels up according to the black algae guide.. and then scrub scrub scrub!
scrub the black algae,and use chlorine diluted and leave it for a day then u can wash with water by scrubbing i think this will give you good result.
 
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acKsw

Member
Jan 19, 2021
14
Sydney, Australia
I nailed my black algae by spreading 1kg of trichlor granules wherever I saw algae. dissolves slowly, algae gone. FC up to 30 for a week. no brushing required. (I started off with TFP liquid shock and daily brushing method, what a chore.. I'll go back to trichlor every time now).
 
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