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Just set up my first ATO for the coral tank and I'm not sure if I calibrated it right. The water level keeps fluctuating. Anyone got tips on how to dial it in properly?

What ATO unit are you using? Some models need a specific calibration sequence. For example, the Tunze Osmolator requires you to hold the sensor at the desired water level during setup.

Yeah, the Tunze can be finicky. I had to mess with mine a few times before it stuck. You gotta make sure the sensor is clean too, or it'll give you weird readings.

If you're using a cheapo ATO, might wanna upgrade. Those things are sketchy at best. I switched to a Neptune ATK and never looked back.

Yield wrote: ↑Sat Jun 21, 2025 3:19 am If you're using a cheapo ATO, might wanna upgrade. Those things are sketchy at best. I switched to a Neptune ATK and never looked back.

Second this. The Neptune system is rock solid. Worth every penny if you're serious about keeping your tank stable.

Thanks for the advice, everyone. I'll check the sensor and maybe look into an upgrade if this keeps up.

Also, make sure your ATO reservoir is big enough. If it's too small, you'll be refilling it constantly, which can throw off the calibration.

I had the same issue last month. Turns out my sensor was too close to the return pump, causing turbulence. Moved it to a quieter spot and it's been chill since.

Double-check the tubing too. If it's kinked or clogged, the ATO won't work right. Happened to me once and I almost flooded my stand.

What's your tank size? Smaller tanks can be trickier to calibrate because the water level changes faster.