Replacing water before Slaming for Algae


New member
Nov 13, 2019
Livermore, California

So I took over my pool care at the close of the season from a service. Service was good but they used tablets giving me a CYA of 90 on my 30,000 gal pool (no SWG). To close for the end of season i slammed it and got a leaf net. I have a big old oak tree that hangs halfway over the pool and i tried to keep up with the leaves but i guess i got too lazy and have a green pool. I'm about to slam it again and use the standard trouble free remedy but I'm wondering if I should go ahead and drain it down to lower the CYA first and make it easier to slam and maintenance in the future? Or should I deal with the algae first?


Mod Squad
TFP Expert
LifeTime Supporter
Jul 7, 2014
Bedford, TX

I would not SLAM a pool if the CYA is more than 50. I would also not SLAM a pool if the cost of the replacement water is less than the cost of the Liquid Chlorine.

In my case, I can fill my pool for less than $60, bucks, so it just does not make sense for me to SLAM.. (Note.. I say that as someone that has never performed a SLAM nor every had to refill my pool..) :mrgreen:


Jim R.


Mod Squad
TFP Expert
Bronze Supporter
May 3, 2014
Laughlin, NV
It would be best to drain 50% or so and then SLAM.

You do need to add liquid chlorine every few days to a week even in winter. Test FC and add as necessary.