I use Fritz RPM Pro for the last 4 years , I do not do water changes, its the only salt that mixes to the parameters I run , and is not a HOT mix -dkh is 8.5-8.8 , where as every other salt i used in the past mixed fresh @ 11- 13 !! My corals like nutrient uptake I have been running this salt in my system longer than alot of peoples tanks have been running , without a water change , I did add a 30 gallon frag tank into the system at the 2 year mark , only water besides top off that has hit the system in 4 years, I get insane growth out of every coral , SPS , LPS,. And regularly save dying /dead corals . My experience is not typical , just sharing my results. ( also never lost a coral in this mixed reef 3 tank 180 gallon Total volume system) Here is the kicker , I am using one of those cheap 50 gpd single stage RODI, for the same 4 years , never changed the membrane and my di resin has been yellow for over a year lol .. That being said , don't do what I do , I have been doing this for 30 years and take full responsibility for my tank and inhabitants. Not really sure how I have such amazing results, some have said its cause I have the OG Godzilla bacteria , and actual real live rock , and a DT with SAND ...... again , not the norm