HCI acid for dark algae?

[MrJ]

Hi,

 

serving my salt water pool now by myself for about 1 year and all is fine - but some dark stain spots (assuming algae) on the grouts....mainly on the bottom 

how to get rid off it? HCI Acid my friend said? If yes how much to apply and how long I cant swimming after the treatment?  I have about 80-90 m3 water, 

 

thanks

Edited July 27, 2020 by MrJ

[Jai Dee]

Your friend is correct.

 

Have a look at this reply in another topic which should give you some answers.

[Bagwain]

It is called black spot. It has a flower & roots.

Common problem with salt chlorination pools which tend to have a high pH! (7.8 to ????

If you have high pH consistenlyl you will get it.

Bast@rd to get rid of.

 

The acid is used to keep the pH down to avoid this issue.

 

To get rid of it. Drop pH to below 7 with hydrochloric acid.

Get some black algacide & do as the bottle says!

Scrub & vacuum!

Do a backwash & then keep your pH around 7.2 with acid.

 

You will need around 2 x 1 litre per week for that size pool!

 

Put 1 litre into a bucket of water & spread around the pool!

 

Never water into acid or direct into the pool! Can swim in 10 minutes if system on!

 

Job solved!

Edited July 27, 2020 by Bagwain