ATO issue.... maybe

[Mandosh]

Is the water level in your ato reservoir higher than the level in the sump?

[Reefie]

Did you use a check valve? Or is the reservoir placed higher than the sump? If so, gravity is creating the siphon, in which case a check valve would work.

[The Grizz]

The ATO pump can not be higher them your sump. It has to be even with bottom of sump or lower, it's a matter of gravity.

[bignose]

peristaltic pump will stop this but I'm not sure of flow rates

[paddyob]

Originally Posted by The Grizz

The ATO pump can not be higher them your sump. It has to be even with bottom of sump or lower, it's a matter of gravity.

It is at the same level.

It is bottom of res... hose goes up... angles down into sump.

Does the angle of the hose have any bearing on it?

[The Grizz]

Originally Posted by paddyob

It is at the same level.

It is bottom of res... hose goes up... angles down into sump.

Does the angle of the hose have any bearing on it?

The output end of the hose into the sump has to be the high point, there can't be a downward flow.

[paddyob]

Originally Posted by Mandosh

Is the water level in your ato reservoir higher than the level in the sump?

The res is tall.

angles down into the sump.

[Mandosh]

Originally Posted by paddyob

The res is tall.

angles down into the sump.

You have to make sure the output of the top-off hose is higher than the water level you run in the reservoir or you're going to get gravity feed.

EDIT:

^^ what he said...

[cale262]

I have a tall res for one of my tanks, much higher than the level in my sump so I ran the top off line to the DT overflow which is higher than both.