Mustard and/or Black Algae

[s.hashemirud]

Trust your tests.

Ignore the pool store testing.

They use "Adjusted Alkalinity" which is affected by the high CYA readings.

New photos

 

[ajw22]

Do a Overnight Chlorine Loss Test and report the results.

 

[s.hashemirud]

I wanted to give you an update. You both were right! They were stains . I used pool magnet plus and now it is much better. Still there are some stains and when I put a heater bypass, i will use jack’s magic to make it look better. Thanks!

 

[s.hashemirud]

What brand and type of chlorine do you recommend for weekly use?

 

[ajw22]

What brand and type of chlorine do you recommend for weekly use?

Depends what you find locally. Brands vary around the country…

Liquid Chlorine - Further Reading

www.troublefreepool.com

 

[JohnT]

FC 2-4. CYA 75. Your CYA is high and your FC level is low. You need to keep your FC up around 8ppm with 75ppm CYA.