Tunze Nano malfunction?

[drknudsenx2]

I got this ATO used, and for the most part it works properly. However whenever i fill my ato container (about 4 gallons), the first time it turns on it dumps a significant amount of water into my sump (the container was about full last night when I filled it). It appears to be filled past the point of the float. After the initial dump of a couple of gallons of water, the water will evaporate down and then when it turns in it will tip properly for about 30 seconds to reset the float the way it is intended.
Does anyone have any troubleshooting advice? When it fills up, it makes my skimmer overflow

 

[Tathamet]

It looks like the water level in both are the same height. My guess would be the water is siphoning in by gravity.

Is the pump actually pumping the whole time? even when passing the sensor?

you may just need to lower your ato reservoir

 

[X-37B]

Get the ato container even with the bottom of the sump.
Make sure the tube pumping the water is out of the water.
The pump should be standing up too.

 

[Tathamet]

Yeah the tube out of the water in your sump as well. I would also try to keep the output of that tube above the waterline of your ato reservoir.

 

[drknudsenx2]

Oh I didn’t think that would be an issue! Awesome, great advice! I will adjust it and hopefully that does the trick!

 

[Tathamet]

Oh I didn’t think that would be an issue! Awesome, great advice! I will adjust it and hopefully that does the trick!

I have the same unit and I think it keeps water from reverse siphoning but can’t see it stopping a forward siphon. Either way I have the output tube out of the water.

 

[Duncan Tse]

Like the above posters said, water level in sump seems to be lower than the RO reservoir water causing a siphon to the sump and continuously dumping water until the water level evens out.

I would take out that bench the RO reservoir is sitting on

 

[Water Dog]

In order to prevent a siphon, the outlet of the ATO fill tube must be higher than the water level in the ATO reservoir. Also, never submerge the ATO fill tube outlet.