Another black algae thread

[melbogia]

I apologize for another black algae thread but I am starting to see black algae in my outdoor pool. The black lines are developing, which is hard to take a picture of but it's definitely black algae. There are also some small black spots here and there. I put liquid chlorine every night. Here are some numbers.

PH: 7.5
CYA: 30
TA: 80
CH: 90
CC: 0.5 or less as measured by FAS-DPD

Overnight free chlorine loss is around 1. I raise my free chlorine every night to 3.5 and it's 2.5 in the morning. I read about SLAM and it says you are done when when CC is 0.5 and overnight free chlorine loss is 1 or less and the water is clear. But I am already at those levels. Do I still need to SLAM? If not, how to I get rid of chlorine?

Perhaps I need more than 3.5 FC every night? My pool is around 20,000 gallons and I put more than a 1/3 gallons of liquid every night.

 

[mknauss]

At what level does your FC get to at a minimum? For your CYA, which is pretty low for your climate, the FC should never fall below 3 ppm.

Read Black Algae

 

[melbogia]

At what level does your FC get to at a minimum? For your CYA, which is pretty low for your climate, the FC should never fall below 3 ppm.

Read Black Algae

Hm I dont' know when it gets to a minimum. What should the CYA be for my climate? And then I can adjust FC to that using the chart

 

[mknauss]

I would think 50 ppm CYA would be appropriate in Sacramento right now. Follow the FC/CYA Levels. Stay above Target level.

You do not follow the SLAM Process for Black Algae. It is a completely different protocol. Read the article.

 

[melbogia]

I would think 50 ppm CYA would be appropriate in Sacramento right now. Follow the FC/CYA Levels. Stay above Target level.

You do not follow the SLAM Process for Black Algae. It is a completely different protocol. Read the article.

Oh I see. Thanks for the correction.

 

[melbogia]

I would think 50 ppm CYA would be appropriate in Sacramento right now. Follow the FC/CYA Levels. Stay above Target level.

You do not follow the SLAM Process for Black Algae. It is a completely different protocol. Read the article.

I need some clarification regarding the chlorine levels. For 50 CYA the target FC is 6-8. I suspect that means FC at the time I pour the chlorine. I put chlorine at night and then it depletes throughout the day. Do I need to put additional chlorine during the day so I stay above 6-8 all day long? Or during raising FC to 6-8 at night is enough?

 

[mknauss]

Technically, if you dose to 8 ppm FC each night, you should be above minimum the next night. But do not miss a day. Or, dose to 10 ppm FC or so, then you should be near 7 ppm FC the next night. Safer. Up to you.

That is why so many of us have a SaltWater Chlorine Generator. They add our chlorine for us every day.

 

[melbogia]

is saltwater pool actually cheaper in the long run? I was under the impression that it doesn't save any money, but perhaps I am wrong.

 

[mknauss]

Cheaper? I would say is about equal. More convenient, absolutely. Instead of buying chlorine all the time, adding it every day, etc, the swcg adds it for you. You buy the chlorine up front.

 

[melbogia]

Oh I see, thanks. If I am interested in converting to salterwater, who do I contact?

 

[mknauss]

If you are handy at DIY -- you can do it. If you want guidance on what to buy, the members here can help. If you want to call someone and pay for the convenience of them bringing the SWCG to your pool, installing it, etc. then contact a pool maintenance company. The payout doing it that way will not work versus chlorinating as you are now. Cost will be about double what DIY will cost.