Green Algae? at Waterline

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Active member
Mar 17, 2010
Tustin, CA (Orange County)

Water chem is right on and there are no issues with algae in the actual pool; however, there is a bright green something growing on the grout right above the waterline. Not sure if algae or moss/mold/fungus.

The 2008 post below mentioned brushing a 50/50 clorox solution on the problem areas:


Is this still an accurate process to remove the problem? Saw "Green Out" mentioned somewhere but not sure if it is used for the same situation or if that product works.

Also, I searched "phos-free" and came up with a couple opinions on it. Just wanted to throw it out there again and get a really good handle on TFP member's thoughts cuz it's something Leslies is pushing hard core and we have been adding to the pool like faithful lemmings. Not sure if it makes a difference for dark bottom pool owners.



Mod Squad
TFP Expert
Platinum Supporter
LifeTime Supporter
In The Industry
Apr 1, 2007
Sebring, Florida
I would simply put clorox in a spray bottle and spray it directly on the grout. It should clear up rather quickly although there may be a slight staining left behind. Brushing with a deck brush and maybe even just a little soap would be helpful in clearing up any residual stains.

Skip the phos-free. You are wasting your money.


TFP Expert
Platinum Supporter
LifeTime Supporter
May 7, 2007
Silver Spring, MD
Phos Free is nearly always a waste of money. If you maintain your FC levels appropriately there is no need for Phos Free.

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