My Cusinart SS-700C single brew Kcup has a very nice auto top off and float valve mechanism... if one is at the store, have a look at the large blue reservoir where the mechanism is for ideas for a DIY that actually looks nice.
The new large Red Sea Max tanks also now incorporate an ATO built in on the side at the back.. kinda cool.

msjboy

neat thanks for the tips guys! I have lots of room in the top of my stand I might build a shelf to hold 5 gallons or RO and have it serve as the ATO to my sump

Thats a pretty good idea. Just remember to clean the intake airline every so often. I find that some of my air intakes like on an overflow vent or intake to an airlifter pump build up salt inside the line.

good point Martin, I'm sure the salt creep could cause some issues, but it all falls under general maintenance

Ive got 2 float switches wired in line with a aqualifter ( just cut into an extension cord ) . With 2 switches its snail proof if one fries theres still a backup switch and it was cheap $4 for floatswitches off ebay . If you get any kind of air leak with the bucket idea it will drain . Oh and everyone whos is paranoid about frying floatswitches with too much currant , an aqualifter draws 3 watts , so at 120 v thats only .04 amps , the switches are rated for 5 amps.

yeah I have thought of modifying this design with either float valves or float switches, I just dont know which one will be more accurate or reliable

float switches can be more reliable as they offer redundancy. For instance you can wire up as many switches in series as you want with each switch slightly higher than the next so if one were to fail the next one will take over. You can also wire in a timer to not only control when the top off activates but also control how long it's allowed to activate for. However such features are more critical when a larger or unlimited source of water is used for top off. If it's a small container that can't physically add enough water to cause damage a simple mechanical float is all you need, provided it can gravity fed. If you need a pump then you'll obviously be better off with a float switch.

well my plan is to put it inside mystand above my sump, and have it drain into the sump when needed

I don't think I'd ever risk it. What if the seal on the bucket or on the valve fails? The whole thing will drain into the sump.


An ATO is relatively cheap. Why even bother with this?

I use this ATO and it works amazing. And it's only 75 bucks

http://www.avastmarine.com/ssc/do/pr...ng/Top-off-Kit

I realize that thats why I'm asking I know there is a risk, but I'm sure that a ATO could fail overtime. it is def. safer then DIY, but I thought I'd put the idea out there ya know?