Hey!
I'm using the Pro Breeze dehumidifier.
It's working pretty good for me. Placed it outside my tent and it controls the room and inside the tent.
It's only a 4x4(1.2Mx1.2M) and the room is probably 6x6(2Mx2M).
It has a 1.8L reservoir capacity but the good thing is you can hook up a hose in the back which backs it much more simple.
I empty the drain bucket once a day, probably about 9L or so..
It can control humidity down to 35% (least it went for me)..
Only down side is the control is digital. So you have to place something on top with some tape so there isn't any light leaks..
Hope this helped.
Good luck and happy growing!