ATK coding 2nd opinion


New member
To anyone who has an opinion or input on the matter, thanks in advance.

I run kalk in my ATO and therefore had to tweak my ATK coding to prevent it from 1) running too long and spiking ph (default 2 minutes) and 2) allowing the ATK to operate up to the top optical sensor. In regards to point number 2, not only would running up to the top optical sensor spike my ph but it would also trigger my alarm (SumpHi). I never understood the default coding that says to turn on if SumpLo is open and turn off if SumpHi is closed.

I tweaked it to shorten the "œon" interval to 1 minute, and instruct the ATK to turn on when SumpLo is open and turn off when SumpLo is closed (vs SumpHi). If That way, if the SumpHi alarm goes off, it tells me something else is wrong, and not that my ATK worked as instructed.

Does anyone have any perspective or feedback on what I am saying? I have a Red Sea 525xl and the ato sensors are positioned near the return section of my sump, which is a small area.

Fallback OFF
If SumpLo OPEN Then ON
When On > 001:00 Then OFF
Defer 000:10 Then ON
Defer 000:04 Then OFF
Min Time 060:00 Then OFF


New member
In theory it should work, provided it doesn't take longer than a minute to fill your return chamber to the correct level. Other wise it will run for a minute, then shut off the whole ATO, it won't run again until you turn it back to "Auto" So there is no harm in having it set to 5 minutes if it doesn't need to run that long. That's the failsafe to flooding or running the pump dry. If you leave the default programming, it doesn't fill to the "high" sensor. Only the "low" one is used. High is the failsafe to shut it off if the low one fails.