I had a similar thing happen to our pool, maintaining the correct FC level for my CYA yet got an algae bloom which I got on top of very quickly and was able to eradicate in a few days. Following the SLAM I performed the OCLT for 4 nights and as it passed every night I was confident it was gone.
Like you, I was following TFP recommendations and did not understand how it was possible for algae to get a hold in our pool.
Prior to our algae bloom we had had no bathers using the pool but we had been experiencing lots of wind that was depositing large amounts of leaves and plant matter into the pool. I was emptying the skimmer basket daily each morning.
After putting some thought into it I found the answer.
I was testing our pool first thing of a morning. Like you we have a SWG, but due to the cost of electricity being more expensive during the peak times i.e. throughout the day, we were not replenishing the pool with chlorine until the early hours of the morning between midnight and 6am unless we had had any bathers using the pool.
So each morning when I tested the pool the chlorine level was always where it needed to be.
However, due to various reasons, which in our case was a very high leaf load and sunny days our FC level must have been dropping below the minimum for our CYA PRIOR to being replenished in the early hours of the following day. So it was a timing issue of when we were running the SWG.
From that experience I now test at the end of the day and I split the run time of my SWG into 3 time periods so as to replenish chlorine on a more consistent basis during a 24 hour period. I also run a higher FC level of 8 with CYA of 80 just to have some wiggle room. Plus during times of high leaf load I empty the skimmer basket at least twice a day.
Could your algae problem be caused by similar circumstances?
Like you, I was following TFP recommendations and did not understand how it was possible for algae to get a hold in our pool.
Prior to our algae bloom we had had no bathers using the pool but we had been experiencing lots of wind that was depositing large amounts of leaves and plant matter into the pool. I was emptying the skimmer basket daily each morning.
After putting some thought into it I found the answer.
I was testing our pool first thing of a morning. Like you we have a SWG, but due to the cost of electricity being more expensive during the peak times i.e. throughout the day, we were not replenishing the pool with chlorine until the early hours of the morning between midnight and 6am unless we had had any bathers using the pool.
So each morning when I tested the pool the chlorine level was always where it needed to be.
However, due to various reasons, which in our case was a very high leaf load and sunny days our FC level must have been dropping below the minimum for our CYA PRIOR to being replenished in the early hours of the following day. So it was a timing issue of when we were running the SWG.
From that experience I now test at the end of the day and I split the run time of my SWG into 3 time periods so as to replenish chlorine on a more consistent basis during a 24 hour period. I also run a higher FC level of 8 with CYA of 80 just to have some wiggle room. Plus during times of high leaf load I empty the skimmer basket at least twice a day.
Could your algae problem be caused by similar circumstances?
