Float valve in eshopps sump

[Valentini89]

So I have the 3rd gen 200 sump from Eshopps just sitting there waiting to be put into use when I set up my system and I had a q I couldn't really find an answer to in the search mode.. what is the float valve for? It's just sitting there in this chamber that for all I can tell has no other use

 

[DesertReefT4r]

If its in the return pump section its for an ATO.

 

[Valentini89]

If its in the return pump section its for an ATO.

Ok so please excuse my ignorance here.. but how exactly does an ato work with sump water?

 

[willembad]

Not sure I understand the "sump water" part of the question, but the float valve allows you to connect a RODI supply line to it - preferably from a reservoir with a capacity smaller than your sump overhead - to keep the level in the return chamber constant by replacing evaporated water.

If you'd like I can post pictures later. Gravity-fed ATO's are not as popular as pumped systems, but I personally haven't had any issues with them. YMMV.