Free Clorine

[thewalk]

I've been battling green algee all spring, I bump my cl up to 15ppm with bleech every night, CYA is 32 cl is 5 right now. I have read that no matter what my TC level is only FC will kill off the algee. I've ordered the Taylor K2006 test kit and await it's arrival. In the mean time how do I raise the free clorine level to kill off the algee.

[fcfrey]

Welcome to the forum, Walk

We will need a lot more information before we can be of specific help.

Mostly how much water is in the pool and the other test results, particularly CYA level.

The conventional wisdom you will find here, will be to use Ben's Best Guess Chart and take your Free Chlorine above shock level and keep it there until the Algae is GONE Then keep it there for another day or two. This will mean testing several times a day and adding bleach to maintain the level above the shock level. Along with that ---- Brush, Vacuum, Brush, Brush, Vacuum, Brush, Brush, Vacuum, Brush,--- lots of patience is required but if you follow the advise here, you will have clear water in no time.

[thewalk]

Ok I got my Taylor test kit today and tested my green water. I have a 13500 gal above ground with a sand filter.

CL 3.0
FC 3.5
CC 0.5
PH 7.8
TA 430
CH 300
CYA 75

I have the next three days off and can give the pool all my attention rather than the quick evening check.

[chem geek]

1) Add 60 cups (3.75 gallons) of 6% bleach (or 30 cups of 12.5% chlorinating liquid) to raise the FC to 20 ppm (per Ben's Best Guess CYA chart for shocking) and monitor and add chlorine as needed to maintain that FC level.

2) After adding the chlorine and letting it mix for at least a half hour (i.e. don't add at the same time), add 50 fluid ounces of Muriatic Acid. This will lower the pH some which will help the chlorine be more effective (if you didn't add chlorine, this amount of acid would lower your pH from 7.8 to 7.5).

3) You might consider using a skimmer sock since there will be a lot of junk in your pool and catching some in the skimmer instead of the filter is easier.

4) Brush your pool sides to expose all of the algae to the chlorine. Run your pump 24/7 during this entire process (from now until your pool is clear) and if your pressure rises, backwash your filter.

5) See this thread for pictures of how chlorine alone will get rid of algae. Have patience.

Your TA level is incredibly high and with your CH and pH levels I would expect to see cloudiness (probably obscured by the green algae) and scaling or precipitating calcium carbonate. After you get rid of the algae, you will need to lower your TA using this procedure, but one thing at a time and focus on getting rid of the algae first. Do you have any idea how your TA level got so high? Did you add a lot of Alkalinity Up (baking soda) at some point?

Richard