Treating brown stains in gunite pool

[jondoepoolguy]

So we have been dealing with some brown stains in the pool since last season when we purchased the house. We have tried a number of things:

• Rubbing lemon on spot (no change)
• Rubbing chlorine tab on spot (no change)
• AA treatment with Essential Values Swimming Pool & Spa Stain Remover (no change)
• Applying Muriatic acid directly to spot with Purity Pool OS Out Spot Stain Remover (made brown streaks all the way to drain). I have brushed these streaks to no avail).

Any ideas on how to proceed next?

PH: 7.4
TA: 90
FC: 3
CYA: 55
SALT: 3000
Calcium Hardness: 214

Pool Details:

• 20,000 Salt Water Pool
• Gunite, Tile, Flagstone
• Pentair Intellichlor ic40
• Pentair Intelliflow 2 VST pump
• Pentair Booster pump (for pool robot)
• Pentair Clean and Clear Plus Filter
• Pentair Mastertemp 400

 

[YippeeSkippy]

Do you know how old the plaster is? Is the plaster in good shape?

There is a stain identification kit on the market we like by Jack's Magic which might help you. Stain ID Kit | Jacks Magic

I'm concerned that your FC is low compared to your CYA level of 60 (55 reads as 60, its logarithmic and not linear).
See this -> FC/CYA Levels

Your CH is a bit low also.

Maddie

 

[jondoepoolguy]

The plaster is from 2016 (when the pool was built). Other than the staining, everything looks in good shape.

Thanks! I look at picking up the stain kit.

I'm working on raising the FC now after the AA treatment (2 weeks ago). Was supposed to keep it low for a while after treatment and then raise gradually.

 

[mguzzy]

I'm curious .. how did you do the AA treatment? if you just dumped this powder in the pool you may not have gotten the AA to a high enough concentration to lift the stain. I just read the instructions. I would get a vitamin C tablet and rub it directly on the stain or put some powdered AA in a sock and rub that on the stain to apply a higher concentration to the area. See if that makes a difference.

 

[jondoepoolguy]

I'm curious .. how did you do the AA treatment? if you just dumped this powder in the pool you may not have gotten the AA to a high enough concentration to lift the stain. I just read the instructions. I would get a vitamin C tablet and rub it directly on the stain or put some powdered AA in a sock and rub that on the stain to apply a higher concentration to the area. See if that makes a difference.

I followed the instructions on the kit (lowered to recommended levels and dumped 1 full container for 20K gallons) and let it set for the requested amount of time. As the stain had not lifted, I repeated the process with a second dose and let set for the requested amount of time before brushing. I did attempt to dump around and on top of the stain.

 

[YippeeSkippy]

Ah..... you hadn't mentioned the AA tx. Yeah, you do need to keep the FC on the low side. Did you add any Polyquat 60 for this period of low FC? Some folks do.
You may find when trying to raise your FC <whenever> that any residual AA will chew it up and out of there.... go slow.

Maddie

 

[jtr8178]

I am having the exact same issue as you. How did you resolve it?