ATO diluting salinity

[wmcinnes]

I have a gate valve on the drain pipe, not a ball valve. The herbie causes the level in the sump to fluctuate very very slowly but still enough to cause the ATO to turn on. Im assuming i just need to spend more time dialing it in and getting the flows to match up, thanks philg3.

I have a refractometer and it reads 1.025 after a waterchange and then a day later the salinity will be 1.024 or 1.023 so that rules out my refractometer needing calibration..

I don't think I can adjust much with this system. Its just a single float switch that turns a pump on when the float drops and turns it off when the float rises up. Maybe I will have to spend some more money and get a more elaborate system. The JBJ ATO is fairly cheap ($70).