A little update. With the zeovit method it requires more frequent SMALLER water changes. I set up my system to do water changes once a month - a 75 gallon water change takes me 15 minutes.
But to do 5 - 10% it didn't work too well, cause my system was designed to drain the entire 75 gallon tank and mix the salt and add the additives in that tank. But if I only drained 1/3 to 1/2 the tank for a 5 - 10% water change, then I wouldn't want to be mixing the salt in that tank cause it would wipe out any beneficial bacteria in there.
My solution was to get a smaller mixing tup and still have everthing hard plumbed to make water changes easy.
Now my small water change process goes like this.
1. Turn pump on from 75 gallon RO tank to pump into cylindrical tank.
2. Add salt/additives into cylindrical tank
3. Let mix.
4. Shut my water change tank off system via valve, then drain however much water I need out of that tank via my "toilet hose"
5. Check salinity of new water and turn a couple of valves to direct water back into system.
6. Turn valve back on to get system running
Fairly simple and still takes about 15 minutes.
(It is a 40 gallon cylindrical tank)
Here are pictures of the new cylindrical tank and plumbing:
