Tunze 3155

Jrod381 · Mar 31, 2020

Need some help, I recently purchased a Tunze 3155 unit for my ATO. Everything works fine except for when I fill the ATO reservoir itself. It seems like everytime I fill it to the top something happens with unit that causes it to dump gallons of water into my sump making the over flow sensors trigger and causing my skimmer to over flow making a mess under the stand. It’s almost as if the pump does not shut off when needed. I t was working just fine for the last 3 days and then last night once I filled the ATO I woke up to the overflow alarm at 4 am. What could be causing this? is an additional float valve needed? FYI it dumped about 10 gallons

lapin · Mar 31, 2020

Under some conditions a siphon can happen. The pump will shut off but the water will keep flowing. The pump should shut off after the full level is reached in the sump (sensor). First step is to see if the pump is shutting off when it should. A solution you can try: have the ato pump exit hose terminate above the ato reservoirs full level. If the end of the hose is higher than the ato's full level it will be hard to have a siphon happen

Water Dog · Mar 31, 2020

Sounds like it’s siphoning. To avoid this, make sure the outlet of the ATO fill tube is always higher than the level of the water in your ATO reservoir.

Jrod381 · Mar 31, 2020

lapin said:
Under some conditions a siphon can happen. The pump will shut off but the water will keep flowing. The pump should shut off after the full level is reached in the sump (sensor). First step is to see if the pump is shutting off when it should. A solution you can try: have the ato pump exit hose terminate above the ato reservoirs full level. If the end of the hose is higher than the ato's full level it will be hard to have a siphon happen

Thanks for the feedback, my question is
Even if the ato pump is at the very bottom it can still siphon up? Wouldn’t it not do that non stop then at that point since there is still water in the ato. My sump height is 20” the hose from the ato exit is roughly about 6” from the bottom, my ATO height is 22” and the pump is at the bottom, am I missing something.