Algae Outbreak

[cmcnitt]

So this is the first time since using the BBB method that I've gotten algae and I'm not sure what to do to get rid of it. It is greenish/yellow color algae. On July 4th I tested the water when I first noticed the outbreak and found this:

FC=3.5
CC=0
pH=7.2
Alk=60
CH=90 (vinyl pool)
CYA=100

I added 3 bottles (182 oz) of bleach and brushed the algea. The pool looked pretty good but cloudy and a greenish tint to the water.

Today, the algae is back and here are my test results:

FC=10
CC=.5
pH=7.4
alk=70
CH=90
CYA=100

I'm not sure what to do now. I was thinking about shocking it but wanted to check with you guys first because you have really helped me out over the last few years.
Thanks

 

[frustratedpoolmom]

So this is the first time since using the BBB method that I've gotten algae and I'm not sure what to do to get rid of it. It is greenish/yellow color algae. On July 4th I tested the water when I first noticed the outbreak and found this:

FC=3.5
CC=0
pH=7.2
Alk=60
CH=90 (vinyl pool)
CYA=100

I added 3 bottles (182 oz) of bleach and brushed the algea. The pool looked pretty good but cloudy and a greenish tint to the water.

Today, the algae is back and here are my test results:

FC=10
CC=.5
pH=7.4
alk=70
CH=90
CYA=100

I'm not sure what to do now. I was thinking about shocking it but wanted to check with you guys first because you have really helped me out over the last few years.
Thanks

With a CYA of 100, that FC level is too low, which would be why you developed algae. On the other hand, CYA tests are not as accurate if you have algae or cloudy water. So was that your CYA before, and are you certain it's accurate?

If it is indeed accurate, see the CYA Chlorine chart for your recommended targets for minimum and shock level, according to your CYA.

Also, if it really is 100, you need to do a partial drain and refill of your water, or you will fight a losing battle with algae all season, or spend a small fortune on bleach trying to keep the levels at the recommended point. JMHO.

 

[JohnT]

Your chlorine is way too low. With CYA at 100, you should never let your FC get below 7.5ppm.

Read this article http://www.troublefreepool.com/category/pool-school/defeating_algae about algae. High chlorine is the key.

 

[cmcnitt]

The CYA is usually 100. My FC is at 10 today, how high should I raise it to kill the algea? The chart says 11.4 is the normal target but I'm well within the minimum of 7.3. Should I go to shock levels or the Yel/Mstrd min 14.9? Also, is my pH and alkalinity OK or do I need to adjust it?
thanks

 

[frustratedpoolmom]

The CYA is usually 100. My FC is at 10 today, how high should I raise it to kill the algea? The chart says 11.4 is the normal target but I'm well within the minimum of 7.3. Should I go to shock levels or the Yel/Mstrd min 14.9? Also, is my pH and alkalinity OK or do I need to adjust it?
thanks

I think they are fine. Yes. To kill regular algae, your "shock" target is good. The Yellow/Mustard is in extreme cases and only for 24 hours or so during the regular shock process. You don't want to maintain FC that high for extended periods, you risk damaging your pool.

The "normal" target is day to day minimum FC. You do NOT want to let it ever go below that, or as you see with your pool, you may develop algae.