Mustard Algae - Starting Over

[mhouser007]

I thought I did everything right...
- got pH to 7.2
- raised and maintained appropriate FC levels based on CYA value (used brand new liquid chlorine)
- brushed and vacuumed entire pool as well as cleaned filter daily for 10 days straight
- left all brushes/hoses/etc. submerged in pool 24x7 between uses
- pump ran 24x7
- passed OCLT
- let FC levels drop and all looked good
- as soon FC dropped below 8 the algae was back
- jaw dropped
...starting over

The only thing I can think of that I might do differently is running the pump at a higher speed.

I figured I start the thread now as I'm not holding my breath that this will work the second time around.

Any additional advice would be appreciated.

 

[PoolStored]

I re-read both of your threads. Both from 2020. Did you just do another slam recently? Was the pool fine for three years? Give us a bit of history.

You are getting a recurrence of algae because your FC is not high enough, at some point. You even admitted in your last thread that if it gets close to minimums (implying it got close or to minimums) you get algae. In the future, I would run your FC at the TOP of the recommended range for your CYA. My guess is you had a few days with higher FC demand and it got close to or below minimums. If I even *sniff* minimums my pool clouds. Link-->FC/CYA Levels

Now, as for the SLAM and drop below 8 and it was back. You named only one of the three slam criteria, OCLT. What was your CC? And, maybe more importantly, was the pool clear? Like no nothing, nada. Even if you scrubbed the walls, nothing poofed up or clouded the water?

We'll help you figure it out.

 

[mhouser007]

I did do another slam recently yes. The pool was fine for 2 of the past 3 years but 1 year ago, after having the pool resurfaced and refilled, I started struggling. First it was climbing Calcium Hardness. I could literally watch it climb in real time to the point where I was getting some pretty significant calcium deposits on the walls and bottom of the pool. Once CH hit 400+ I emptied half the water out and refilled. CH is around 210 now. I still get a few deposits here and there but it is 90% better. After that the algae started and was quite persistent so I decided another slam was in order. You are correct, this is likely user error as I did let the FC get a little low a couple of times and it is getting quite warm now. The pool temperature is about 84. Having said that, thank you, this site is great, the one thing I forgot about was that I should keep my FC at the appropriate level based on my CYA value. I was trying to keep it between 3-5 but now realize that was too low for a CYA of 40, where I am now.

I started another slam yesterday.
FC = 20.0
CC = 0
PH= 7.2
TA = 50
CH = 210
CYA = 40

I took the readings after dark last night and this morning, 8 hours later before sunrise FC was at 20.0 still, CC was 0 and I really don't see much dead algae so I think I am in half decent shape.

Thanks again.