No Free Chlorine Level

[dltodaro]

My CYA level is 52.

I have a gunite pool. How can I remove all of the yellow algae? I have some stains on the wall. Also do I need to shock the pool to make sure I have killed all of it?

Thank you,
Debbie

[Watermom]

Yes. Take a look at the Best Guess Chlorine Chart in Ben's signature above for needed shock levels. Don't worry about the stains for now. Just work on killing the algae and you can take care of stains afterwards.

[PoolDoc]

+ Get a cheap OTO kit, so you have a reliable (if not super accurate) way to measure chlorine.
+ Start adding 3 gallons of PLAIN 6% household bleach each evening.
+ Brush the pool completely after the 2nd dose.
+ Continue till you get your K2006
+ Report complete readings once it arrives.

[dltodaro]

I did purchase kit and post results.

[PoolDoc]

My bad.

CYA = 50 ppm; mustard algae level for FC is between 15 and 30 ppm.

+ Add a first dose of 6 gallons of plain 6% bleach.
+ Make sure NOTHING is in the skimmer (no dirt, no chemicals) and pour the bleach in via the skimmer while the pump is running.
+ The following evening, add enough chlorine to raise the level to 25+; then brush the pool completely, then add another gallon of bleach.
+ Hold the chlorine level between 15 - 30 ppm for 1 week after all traces of mustard algae are gone

[dltodaro]

Thank you. To avoid multiple trips to the store how many gallons do you suggest I buy? I have never used bleach before. Thanks

[PoolDoc]

Probably, 24 if you can get that many -- enough for 4 days. (Lots of jokes around here, about the weird looks you get when you're in the check out line with 25 gallons of bleach and 10 boxes of borax!)

[Watermom]

Just tell people that you have really, really dirty kids!