ato and water replacement questions

[Blahenazo]

Hi

The problem I have with the above set up is when automating larger water changes, the return pump can not be turned off at the start.

The reason for this is that if the return pump is turned off then the water that flows over and resides in the overflow boxes and pipes will drain down into the sump and raise the level of the float switches in the sump above the original auto top up levels. This would complicate the automation when trying to return the levels to the normal levels after refilling the salt water.


Can this be achieved?

you say it complicates auto-waterchanges => the matters if you turn off your return pump , because you will not know the amount of water will ato-ing.

This is incorrect because you do know the quantity ( it will always be the same (from max water above ato , to minimal sensor ) because of your ATO that was active before the auto-water change keeps its at the same level so the cycle will always start with the same amount of water so you don't need a level to the top quantity , ( as long you you fill long enough with new water, time the time it takes to let the pump reach the level + add some extra seconds.

after switching on the return pump after the ATO water change , if you over filled ( small amount , since you timed it and you will never over fill since the timer is prevent that )

its even better to under fill a small amount , your ATO will top off this minimal amount like it would normally do.

Xiaans solution is KISS and its proven its works , yours seems to be very complex and might be impossible with the profilux. ( switching functions of level switches depending on states
also big water changes , or 2 smaller ones , its doesn't make alot of difference. Both have pros and cons.
)