High CH and Green Algae stains - pool store saying that algae "embedded" in Calcium crystals

[Thilding]

I am new to this helpful forum and with your assistance performed what I thought was a successful SLAM around 2 weeks ago. FC levels stable, no CC and water clear for days. My problem is that I continue to have green algae stains along the sides and bottom of my pool. The algae stains are worst in the deep end and anywhere there is a lot of shade. I used a chlorine puck and was able to scrub green stains off so I am fairly certain I am dealing with algae. Repeated water tests at Leslie's pool store show 0ppm copper and iron.

My CH level is very high - 900ppm - but I cannot drain my pool right now because I live in the desert and daytime temperatures are always over 100 degrees. I do plan on draining the pool as soon as the weather cools.
As hard as I tried I could not brush the algae from the pebbletech surface and the local pool store staff think the algae has become trapped in the calcium scale. They recommend that I treat the pool with an anti scale chemical after swimming season is over, leave it in the water for 3-4 weeks and then drain the pool. They are telling me that the algae should release with the calcium from the pebbletech.

My question is this - is it plausible that I would still have algae stains after a successful SLAM in a pebbletech pool with high CH and very high round the clock temperatures? Or is it more probable that I did not successfully complete my first SLAM?

Thank you in advance for any assistance you can provide ~ Theresa

 

[DuaeGuttae]

When we bought our house about two years ago, we had algae stains embedded in calcium scale. It showed up quite well on our white plaster. I continued my first SLAM way longer than necessary because I was viewing it as visible algae, until my husband convinced me that it was stained scale. We learned how to watch CSI because our calcium was pretty high (not 900 though). By keeping our pH under 7.7, we could keep CSI in the negative range, and over time (and probably helped by brushing), the scale dissolved. We never did an official drain and refill, but last fall we had an amazing amount of torrential rain that did cause us to keep lowering water from our pool. Our calcium dropped, and we try to top up from stored rain water when we can. I like being able to let my pH ride just a bit higher while still keeping my CSI negative.

I’m not sure of all the details of your SLAM, so I can’t really speak to how successfully you completed it. It sounds like you’ve met the three criteria for passing, though. I did just want to say that with high calcium if you aren’t keeping your pH down pretty aggressively, you’ll definitely have a tendency to scale, and algae stains can be embedded in it. At least in my case, though, it came off without chemicals to remove it, just through using muriatic acid to push my pH down to 7.2 every time it went up to 7.7. Maybe someone with more knowledge can say whether that would be expected.