Large Brown Spots on Liner - organic

[charliep]

My water is crystal clear, my FC is 12.5, PH 7.6, ALK is spot on, CYA - OVER 100! I used BioGaurd Super Sol to open my pool this year and my FC levels have never dipped lower then 10.

Over the past 2 weeks I have seen large brown stains in my liner. I tried the Vitamin C test and it did nothing. I tried the puck test and it worked. Whatever it is it will not brush off without direct application on a puck. The whole pool needs to be treated to get rid of the staining. Should I just shock it with bleach?

25K gal, IG vinyl, 1/2 HP Jacuzzi pump, 200 sqft cartridge filter, Polaris 280 cleaning robot, built in 1999, new liner in 2012, Live in Crystal Lake, IL

 

[jblizzle]

Welcome to TFP!!!

Ideally you would replace water to get your CYA into the reasonable range (how did you test the > 100ppm?) and then follow the SLAM process with a lot of brushing to try to lighten the stain. [slam:1utcfcf8][/slam:1utcfcf8]

 

[charliep]

TFP Rocks!! Thanks for the quick response.

I tested the CYA myself with a kit.

I also have .04 copper.. do you think it could be a copper stain? I spoke with the owner of one of the largest pool stores in the Chicagoland area and she thinks it's a fungus growing behind the liner?? I told her it disappears if you let a puck sit on it for 5 minutes and she said the pucks are so powerful they can kill fungus through the liner... very hard for me to believe.

I am going to SLAM.

 

[jblizzle]

Confirm how high your CYA is by starting with a 50/50 mix of pool water and tap water. Then add the reagent and double the reading. This will give you a better idea about how much water should be replaced prior to starting to SLAM.

Since the vitamin C did nothing, it is not a copper stain.

 

[charliep]

image for others to reference in case they have the same issue

 

[jblizzle]

Those are weird looking stains and not typical of algae in the pool I don't think. I know nothing about fungus behind the liner.

 

[charliep]

AMAZING RESULTS. I Slammed yesterday evening and today the stains are 90% gone. I am going to give it another night and it should be completely gone.

Question: Is it safe to swim in the pool after SLAMin? FC 30ppm, CYA 150

Thank You!

 

[jblizzle]

Well, you are not exactly SLAMing because for a CYA that high you likely would need the FC up around 40+ppm. But as long as you pass the 3 criteria to stop, you are safe to swim when the FC is below shock level ... so 30ppm should be fine.