Algae problem, can't figure out why

Rage4order

Member
May 10, 2021
16
San Antonio, Tx
For the last few weeks I have been battling an algae problem. My test numbers have been good and I've been keeping up with my chlorine. I will say my pool does not get used a lot so the only "circulation" it gets is from the pump/filter. Could this "stagnation" be the cause of my algae problem? Here's my most recent numbers-FC 4, CC 0, TA 120, CYA 40, and pH 7.3. I have already had to floc and vacuum twice in the last 5 weeks.
 

wireform

Silver Supporter
In The Industry
Aug 15, 2017
2,925
Spring Valley, NY
Well let me start, cya of 40 has a target of 5-7 so probably you were below once too many and that's how algae takes hold. Floc isn't supported much here and will mess up your filter which can be another reason why you have the algae. Chlorine is the only chem that will rid the pool of algae. You have to deep clean the sand filter and maybe even change out the sand if you can get the sand cleaned up. Afterwards you need to slam the pool .....
 
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HermanTX

Gold Supporter
May 20, 2020
2,528
Katy TX
For the last few weeks I have been battling an algae problem. My test numbers have been good and I've been keeping up with my chlorine. I will say my pool does not get used a lot so the only "circulation" it gets is from the pump/filter. Could this "stagnation" be the cause of my algae problem? Here's my most recent numbers-FC 4, CC 0, TA 120, CYA 40, and pH 7.3. I have already had to floc and vacuum twice in the last 5 weeks.
You do not say but I assume you use liquid chlorine as there is no mention of a SWCG in your signature.
By “keeping up with my chlorine” are you dosing daily or are you on a more infrequent schedule.
My concern is that your FC is 4ppm but is it dropping below that between your chlorine additions? This is where algae can start.
In summer, especially in Texas, it is best to be at the high side of the range on FC to keep it safe.

I use liquid chlorine and dose twice daily To keep my FC constant.
 

Rage4order

Member
May 10, 2021
16
San Antonio, Tx
Well let me start, cya of 40 has a target of 5-7 so probably you were below once too many and that's how algae takes hold. Floc isn't supported much here and will mess up your filter which can be another reason why you have the algae. Chlorine is the only chem that will rid the pool of algae. You have to deep clean the sand filter and maybe even change out the sand if you can get the sand cleaned up. Afterwards you need to slam the pool .....
When I floc, I do vacuum to waste. Are you talking about the residual messing up the filter? I will say the sand in my filter is about 4 years old.
You do not say but I assume you use liquid chlorine as there is no mention of a SWCG in your signature.
By “keeping up with my chlorine” are you dosing daily or are you on a more infrequent schedule.
My concern is that your FC is 4ppm but is it dropping below that between your chlorine additions? This is where algae can start.
In summer, especially in Texas, it is best to be at the high side of the range on FC to keep it safe.

I use liquid chlorine and dose twice daily To keep my FC constant.
Yes, I'm using liquid chlorine. I have been adding about 16-20 ounces every other day. It appears maybe I need to add chlorine daily?? Maybe 8-10 ounces twice daily?
 

HermanTX

Gold Supporter
May 20, 2020
2,528
Katy TX
Yes, I'm using liquid chlorine. I have been adding about 16-20 ounces every other day. It appears maybe I need to add chlorine daily?? Maybe 8-10 ounces twice daily?
I would change to twice daily dosing. for example, I raise my FC to 6ppm and I lose 3-4ppm throughout the summer days. So I calculate what I need to replace (use Pool Math app - the “effects of adding“ is in the drop down menu) and split that over 2 doses. I do some in morning and then in late afternoon. If I am swimming that day, I may add a little more. So I maintain 6ppm throughout the day . I test sometimes daily or at least every 2nd day and everything is on track. Hope this helps.
 

Rage4order

Member
May 10, 2021
16
San Antonio, Tx
I would change to twice daily dosing. for example, I raise my FC to 6ppm and I lose 3-4ppm throughout the summer days. So I calculate what I need to replace (use Pool Math app - the “effects of adding“ is in the drop down menu) and split that over 2 doses. I do some in morning and then in late afternoon. If I am swimming that day, I may add a little more. So I maintain 6ppm throughout the day . I test sometimes daily or at least every 2nd day and everything is on track. Hope this helps.
I will try switching to twice daily dosing and I'm gonna go ahead and change the sand in my filter. Let's see what happens.
 
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