A tale of 2 tanks---or---running rodi for marine and Amazon River discus;


Staff member
RC Mod
I have a nice setup for ATO (autotopoff) in which my ATO feeds from a monster ro/di tank (basement) and all was fine until we acquired a demanding freshwater tank (discus need a 6.5 ph in freshwater, which of course has no salt in it and does not want unscheduled minerals monkeying with the ph.)
So rather than cram another reservoir into our basement, I took a look at new equipment, and went with a Tunze Osmolator 3155 and its partner, the Tunze Calcium dispenser, smaller than a liter soft drink bottle. The beauty of this setup is you feed it calcium powder once a week, and in effect, it delivers the resulting kalkwasser (calciumwater) to your tank for stony corals and clams, and doesn't require a stirrer or reactor, or whatever, if Kalkwasser suffices for the calcium demand of your corals.

The Osmolator is an efficient autotopoff unit. That's its job. It can draw ro/di from my monster reservoir and mix it with kalk in the Calcium Dispemser, which sends calcium to the tank along with the regular topoff. IE, it's a calcium source that feeds in along with your reguilar topoff. Even better, it can use any calcium hydroxide, meaning even fairly economical Mrs Wages Pickling Lime. This means also that your ro/di reservoir stays pristine, available for any other ro/di use you have.

Neat development, easy use, small footprint.