Why not make your own little 3 gallon drip top off with a container and an IV hose or some other kind of clamp/valve? Mine cost me $5 for the container. It's how I drip my kalk.
I want something that I can use to replace evaporated water for a few days so that if I wanted to go away for a few days, it would take care of it. Is the only thing I need is a float switch and a container of some sort like another tank?
I don't even have a float switch. I have a rubbermaid type container on a milk-crate type storage thing under my tank. I drilled a hole about an inch up from the bottom and put an IV dripper in it. Took a few days to figure out how fast to drip it into my sump, but now it's all set. I have a 75 g with pc's and lose about a gallon - gallon and a half a day to evaporation, so I refill the bucket every 2 days.
I use a Liter meter on my 150. I have a 35 gal RO\DI holding tank outside. This will last me about 7 days, maybe longer during the winter\cooler months. I used to use just a float switch that controled a small powerhead that was inside the drum. The only problem with this is when\if something gets on the float like a snail or crab, the switch will activate and empty your holding tank in minutes. This happended twice in one week to me. I didn't relize what the problem was until the second time. I had thrown a snail in the sump by mistake. The powerheads just pump to much water too fast. The liter meter is made for salt water top off,can be set to pump as slow as you want it, comes with its own float switch so you can set it to pump just a little more then needed.
