Do borates help suppress algae?



I just got back from vacation and expected a green pool. It didn't happen!
Here's the background:
Been running borates at 50 ppm for a few years now but I was going to be away for 12 days so I shocked the pool and spa (25 PPM), turned off the pump and SWG and hoped for the best. I expected to come back to a green swamp (No big thing since I know how to fix that) and was VERY surprised to see the pool as clear as I left it and the spa only very slightly tinged with green but not cloudy. Of course when I tested the water there was no chlorlne left (no surprise here).
I shocked the pool and spa with bleach (20 PPM) after starting everything up this morning and tested it again this evening and everything is clear, FC 12 ppm, and no CC!
I KNOW it's the borates because my pool SHOULD have been a green swamp after 12 days of no chlorine OR ciculation!
I was already sold on borates but I know now that they are very effective at preventing and slowing algae! I have the proof I need.

chem geek

TFP Expert
LifeTime Supporter
Mar 28, 2007
San Rafael, CA USA
Excellent! Welcome back from vacation -- I thought something had happened as there weren't posts from you for a while. Hope you had a great time.

It's good to hear a real-life example of the Borates inhibiting algae growth. It's supposed to be the case at least a little bit, but it's nice to have a real-world example. A great insurance policy with other side benefits of sparkling water and pH buffering.


Well-known member
May 25, 2007
I've got borates now, and will be gone for about 5-6 days in August. I had planned to shock before we left, then cross my fingers and hope for the best.

Your post gives me hope :)