ATO freshwater container?
 

I just ordered the Hydor Smart Level Auto Top Off Controller and Eheim Compact Pump 600 to put a ATO system together for my 122 Gallon FOWLR system with a 60 Gallon Sump. What does everyone use to hold the freshwater for their ATO systems? Also I was planning on using a rubbermade garbage can and wanted to put it beside my tank 2' off the ground, will it be a problem having it this high or should it be level with the sump?

I use a 30 gallon tank for ato water. Be careful with your ato container higher then the sump you may create a siphon and drain the entire thing.

A garbage can would work just fine but I would have it hidden. I have used a tall column type aquarium for one holding tank and built a section directly into my sump on another aquarium.

The reason I wanted to use a garbage can is so I have enough capacity for when I go on vacation and the friends that are taking care of my tank don't have to fill anything. I figured it should be good for the 2 weeks I am gone.

If I have the discharge hose for the ATO not submersed under water I was thinking then I wouldent have a problem with siphoning back, or will I run into other issues?

It's always a good safety feature to have a smallish fresh water top off container, say a five gallon bucket. That way if some thing fails in the auto top system and it sticks on or a syphon is created you don't flood your tank with to much fresh water. Another float switch/ timer can feed the five gallon from a larger storage container.
Very important it can't continue a syphon for sure.

I use a clear plastic sterilite bin (kind with the white lids). It's about 5 gallons, and he a float valve in it, and a ball valve that only let's it refill very slowly from the RO storage container... (so if something happens with the topoff process, there is limited water that can be added.

I've only sized my ATO reservoir to hold no more fresh water than the empty part of my sump can handle without over flowing. I would personally use a smaller reservoir and have 5g pails of fresh water for your friends to add if needed. You can even leave them a powerhead with a hose attached to fill the reservoir up without having to even lift anything. The garbage can would probably work just fine but there is always a chance it will fail and put a lot of water on your floor in a very short period of time. I do things my way for my own peace of mind and this is all just my own opinion.