Algae: new to TFP

[Adpaddock]

Things were going swimmingly until I return from vacation to a slightly green pool. Pool store advised Zappit shock (73% calcium hypochlorite). The pool cleared up and was looking good. We cleaned filters, brushed, and cleaned up floats... The chlorine levels were high for about a week...in the 20's. My CYA was 80, but pool store said that was great. FC went down to what I think is the standard (3-5) and a few weeks later the algae starts appearing in the corners by the steps. I put in 8oz Zappit, the pool looks clear again. The pool store is telling me I should just put the zappit in the pool every week as part of my routine. After reading TFP, I'm not going to do it. I'm assuming I need to drain water, stop using pucks and go with liquid chlorine, bleach. How much water do I need to drain? The water table is very high here in Florida.

my numbers:
Fc= 10
CC= 0
PH= 8.0
CYA= 90
TA= 110
CH= 280

 

[atttech-2]

Welcome to the fourm

Pool Math link will tell you how much water to replace based on the target CYA you set. Sound like you know to not drain too much at one time based on the water table comment. It is possible to SLAM with CYA of 90 it is just that it can be expensive, so if you like you can strike a balance do some drain and fills to get the CYA to the 60 or 70 range then read and follow the SLAM directions in Pool School. Once you have the pool under control a CYA of 60 is not such a bad thing and you can always lower it a bit more this winter with rain water fill and drains.

 

[Adpaddock]

Thank you! We drained and filled and the CYA was at 50! Yippe! We are into the slam process! Thanks!

- - - Updated - - -

Another quick question. Going forward we will be using bleach and not pucks. When we go on vacation, and use the chlorinator with the pucks, what can we expect to happen to the CYA in a week?