Polyquat algae prevention question

I often get algae in a few places in my pool. On a grotto shelf, another step into the pool which is near the spa spillover and a few places on walls. Nothing drastic however it is annoying. I brush and keep the chemicals ok, however it seems to come back after only a day or two.

Water temp has been around 74 and rising, I have chlorine right now at 9 PPM seeing if that will help but normally I run at 3-5 PPM, CYA is about 40. I have a cartridge filter and navigator sweep which can get most of the walls but obviously not the steps or shelfs.

Would polyquat help with that ? Or is it mainly to prevent a full out algae bloom ? Is there anything I can do to prevent this from coming back other than brushing every day ?

thanks,
-- john

It won't hurt to add an algaecide. Just make sure it is polyquat 60%. Perhaps you don't have as good of circulation in these areas? That may be why you are getting some algae in these certain spots? Just a speculation.

yes the circulation on the grotto shelf is not great and it's probably in the shade most of the time.

As for the other spot it collects is on a step from my baja shelf into the pool and this is right near the spa spillover so I would think circulation right here would be excellent however it collects like crazy right there. The sweep can't get to it. I have to brush it.

I might try the algaecide and I am keeping the chlorine level high right now to see if it will prevent it from coming back.

thanks,
-- john