Replacing water to get rid of CYA

[salinda]

I have a cartridge filter and you are right, there is no multiport valve for the filter. There is a drain port at the bottom of the filter.

[xcapecod83]

Thanks for all the great information! My cartridge filter cannister has a drain plug so I can drain the water when I clean the filters. It's too big for a hose, but there's a drain near by. Can I drain water this way without damaging my system?

[salinda]

I don't know about draining through the plug. Maybe you can....

What I have is a brass ball valve with a standard hose bib thread on it plumbed into my system between the heater and the filter. I run a hose from that to a nearby sewer cleanout. With the pump on, I open the valve and it can drain the pool very slowly. Of course, I turn off the autofill with this setup. I am thinking that if I left the autofill on and closed the skimmer, I would be draining from the bottom and filling from the top I can do a suboptimal water change that way too.

Moot point for me since the rain dilution this year took care of the problem.