First time dealing with green algae

[Shane112358]

Hi all, I got this pool at the beginning of the summer and all went great until a few weeks ago. What started as a load of sawdust from neighboring construction has turned into a green algae bloom and I admit I don’t know what I’m doing. I was nearly out of the woods and then my SWG wasn’t working and it returned quickly with a vengeance.


Test results today- Fc 5.5 CYA 55 pH 7.8
Just added 2 lb of 68% hypo clo shock and 2.5 quarts 14.5% acid. Should I adjust my CYA as well now or wait? I’m still filtering 24/7 and backwashing 1-2/day.

 

[Shane112358]

By the way I added that much acid bc I am still trying to get my TA down, so I’ve been playing the game of knocking down pH to 7 and then agitating to bring up, repeat etc. I realize now I should have waited to do that but it’s been going up quickly lately bc of the algae so hopefully it’s not an issue

 

[mknauss]

You have a great test kit and you just need to follow the SLAM Process

Your CYA is 60 (round up). Raise your FC to SLAM level based on FC/CYA Levels (non-SWCG chart as you do not use your SWCG during a SLAM). Use liquid chlorine to raise your FC. Lower your pH to 7.2 prior to increasing your FC. Then only test FC during the SLAM,
Maintain your SLAM level FC until you pass the three criteria.

 

[Shane112358]

Thanks - so I did the SLAM targeting 24ppm FC and I also decreased pH to 7 so I’m more or less right on target there.
I’ll follow three criteria for SLAM and leave CYA alone for now
My previous mistake is that I fought it off successfully without SLAM but then my FC dropped to 0 without my knowledge and it returned. I misread directions and only used half the SLAM FC suggested.

 

[mknauss]

Sounds good. For this time of year, no need to add CYA until March or April. UV impact is diminishing quickly. Once complete with the SLAM maintain FC at 7.5% of CYA level.
Also, never use cal hypo in your pool with the hard water you have. Use liquid chlorine.

 

[Shane112358]

Haha okay. Good to know. What is the Consequence of using cal hypo with hard water ?

I’ll stop using cal hypo to maintain SLAM and only use bleach.

 

[mknauss]

Cal Hypo is Calcium Hypochlorite. It is adding calcium every time you use it. Hard water is all ready high in calcium.
Have you tested your CH with the test kit?

 

[Shane112358]

I did not but recently. A month ago I was at 300. Thanks for the tip, I have been using bleach to bring up FC in the past but for SLAM I thought we had to use the shock for some reason. I’ll use bleach every time from now on