Tunze Osmolator 3155 ATO Problem

rube_ · Nov 18, 2016

Hello, I am having a problem with my Tunze Osmolator 3155 and am hoping I can find some answers here. Thanks in advance

I feel like this would be a common problem with an easy fix.

Here is the issue_
When the water is low in the sump, the Tunze Osmolator 3155 pump turns on, it fills to the point when it reaches the sensor and the pump then goes off, which is how is should work. After the pump goes off the water continues to come out of the tube in a dripping fashion and overflows the sump far beyond where the sensor is set. Could it be a siphon issue or something. The water line in my ATO reservoir is higher then where the end of the hose is located in the sump. At the moment, I have the hose higher then the water line in the reservoir letting the water drop much further then i would imagine normal and the Tunze Osmolator Universal 3155 works as it is designed. Is there anything you could suggest that would work to alleviate this problem, maybe a check valve or some other kind of valve etc. I did some googling and saw that some people did that and then put a PVC tubing at the end of the hose putting the water closer to the return tanks water line. Also, is there someone in the USA that handles there technical assistance?

alyee5 · Nov 18, 2016

yep that what I did....I have the ATO line clamped higher than my reservoir and have the water go thru a 1/2" PVC tube into my return section in my sump a few inches above the sump highest water line (ie when the return is off)....

mcarroll · Nov 18, 2016

Roger Vitko runs their USA operation and has always been a pleasure to deal with.

Tunze has a support forum here on Reef2Reef.....I asked if a mod can move your thread, but you're welcome to post there too!

Tunze.com website has their direct contact information, including phone and email.

hybridazn · Nov 18, 2016

Most likely the issue is because your ato water level is higher than the water level in your sump. So in a nutshell, gravity is causing a siphon and it won't stop until both water levels are equal or you install the hose up higher than the ato water container. I had this issue with mine and what I did was install a one way air valve to break the siphon when the pump was off.

sinekal · Nov 18, 2016

You caught your own problem. You create a siphon when the pump turns on. It will drain your reservoir each time. The only option other than raising the line like you have done is to get that switch accessory and use a peristaltic pump like the one avast makes. That's a fairly expensive route so I personally would go with plumbing a pipe to feed the water back down like you mentioned.