I change mine out about every 6 months or sooner if they need it. If my sediment and carbons look dirty I change them. The di
resin I also change out every six months or so, but by the time I do it the TDS
is about 1-2 coming out of the good water tubing.
It's really up to you, the less TDS
you have going in the better but if its around 1 or 2 then I wouldnt stress it really.
I do not know what type of kind of ro
unit you have, mine for instance from brs will take any standard cartridges. The di
resin you just fill up after emptying the garbage di
. The membrane, which is usually on top going sideways, needs replacement about every two years or so.