I have the 5 stage ro/di from aquasafe... the big bugger...
But with the fresh i added every other week just to avoid any unforseen mishaps..... I guess its overkill with the ro system.....but I have like.....gallons of it still so... I though it wouldnt hurt
Almost bought a doser for just that stuff with my stingrays but managed to do it manually and avoid it..... could have been my top off system