ro auto top off plan - thoughts please?

I was planning on installing an RO unit, under my tank (well actually just adjacent to it) connected to an auto top up unit.

I found that my previous 180 lost about a gallon per day evaporation. Adjusting like for like, the new tank will probably loose about 1.3 gallons (8 litres in Euro-speak) - the tank is 8x2x2.

Having never owned an RO unit, and not being entirely familiar with the devices, I was suprised to read that the first gallon or two of water should be run off to waste each time you use the unit. If this is so, then is my plan to use an RO unit connected to a top off controller flawed?

My plan was to further improve this set up, and run the top off water through kalk stirrer - there by killing two birds with one stone.

I would really apreciate folks comments - if I am to proceed with the RO idea then I need to do before the cabinet etc is fitted.




New member
Mine is not automated yet, but it might be easiest for you to get a big brute trash can with rollers underneath as a reservoir. You can just fill it up when it gets low. From what I understand it's not good for the membrane to only take small volumes of water at a time. But get the RO/DI unit. Its probably the wisest decision I have made for my tank.


Premium Member
There are people that will tell you never ever hook an RO unit directly up to you're tank using an ATO. The reason being that if the float switch fails, you end up floading your entire tank and killing your livestock. I tihnk this is sound advice. Is there anyway to hook the RO up to a ATO reservoir? At least if the switch fails there you only flood your floor. :)

BTW, I believe you're only not supposed to use th first two gallons if using new filters. Not every time.
I don't really have a space to house a resevoir close to the tank, and at a rate of say 1.5 gals a day, then we are talking at least 10 gals a week, so I would really want something in the region of 15 gals to allow for the odd day that I forget to up the reservoir etc.

Thanks for the input.