Successful SLAM (I think) but still algae

[NSBFAN]

Hi all, I've done a few SLAMs over the years and always had success, but this time seems to be different. I went through the process and it seemed successful. I have a pebble finish concrete pool 14,000 gallon. My CYA is 30 so I put the SLAM level to 12 and kept it there until it met the criteria of minimal overnight drop, less than 0.5 CC using Taylor FAS-DPD and water clear. I brushed and vacuumed and cleaned the filter daily and ran the pump 24 hours a day for the days. I achieved that three days ago. Today, here were my numbers:

FC - 7.2
CC - 0.0 all clear
TA - 60
Calcium - 310
PH - 7.6
Borates - 30
temp 84 degrees

The water looks very clear and the testing says it should be clean, but I noticed a couple patches on the bottom and when I brushed it, of course it seemed to be algae. The brush poofs it like a sandy greenish/yellow residue. Is this a situation where it simply got algae again? And how so if my chlorine is at the level it is with no CC?

Thanks for any advice and help.

 

[Texas Splash]

Maybe pollen? Do you see anything like that around the pool, on cars, decking, etc?

 

[NSBFAN]

Hi Pat. Our pollen season is over so that's not it. Funny, during peak pollen when my whole deck and everything is yellow, the pool seems to filter it fine. I just have to clean the filter more.

We have had a few big rains. Could it be some fine material that isn't algae? It's definitely greenish yellow color.

 

[Texas Splash]

Could it be some fine material that isn't algae? It's definitely greenish yellow color.

It's possible. Also consider if there was any chance that anything may have washed into the pool from all the heavy rains. In either case, your numbers look good, so without an unusual FC demand it might be something other than algae. Still, if it doesn't go away or lighten in the next day or two, or gets worse, you could always do another Overnight Chlorine Loss Test to be sure.

 

[NSBFAN]

Thanks. I vacuumed and brushed and did the filter and yes, I'm going to do the OCLT tomorrow if the stuff remains.

 

[Auburn02]

Thanks. I vacuumed and brushed and did the filter and yes, I'm going to do the OCLT tomorrow if the stuff remains.

How'd this turn out? I've found myself in a similar situation recently, after a week or so of brushing/vacuuming and the test results looking just fine the entire time, I finally opted to just start another SLAM.

 

[Lemonhead]

I have green spots appearing on the bottom of my pool all the time. I always brush and vaccume. I never have cc higher than .50. Always maintain adequate fc. I think I might add algacide

 

[Katodude]

Algaecide is a bad idea. At best it will do nothing, at worst it will add copper. You want to get rid of Algae the answer is always more LC.

 

[NSBFAN]

How'd this turn out? I've found myself in a similar situation recently, after a week or so of brushing/vacuuming and the test results looking just fine the entire time, I finally opted to just start another SLAM.

It turned out well. I've been keeping my FC on the high side around 6 and it was great until today I noticed something when I brushed. My FC is 6.2 and CC was .2. water very clear. So I'm starting to suspect it may just be dirt or pollen after large rains. It looks greenish but it isn't in blotches or spots, I can't really see it until I brush. Maybe I just need to brush/vacuum more frequently during these months. I did used to run a sand shark more often.