ATO and Variable Speed Pump

[Reflective]

I just got my Waveline return pump working with my APEX, and I would like to ramp it up to 100% for part of the day.
The problem I am having is that when it is ramping up to 100%, the water level in the sump keeps dropping so my ATO keeps trying to fill it. I've been turning off the ATO while it ramps up, otherwise I know it's putting way too much fresh water in there. Are any better solutions?

 

[ReeferBob]

You should not vary your return pump rate if it effects the level of the tank. I assume with a higher rate of return (100%) that your tank level is increasing causing your return level of the sump to drop and the ATO is triggered. I suggest you leave the return pump in a balanced state and use other means to increase/decrease water circulation.

 

[Jimbo662]

You should not vary your return pump rate if it effects the level of the tank. I assume with a higher rate of return (100%) that your tank level is increasing causing your return level of the sump to drop and the ATO is triggered. I suggest you leave the return pump in a balanced state and use other means to increase/decrease water circulation.

Also, if you increase your return you would need a way to adjust the drain to match.

 

[gtbarsi]

Also, if you increase your return you would need a way to adjust the drain to match.

I agree 100%
Return pumps are generally either on or off. Variable speed pumps are great for allowing you to tune your return to your drain minimizing the amount of potential adjusting you have to do to the drain with a valve. Once you find the equilibrium point for your drain and return your return pump should either be on or off.

The reason the water level is dropping is that your drain is not keeping up, when you ramp up the return pump. As you have seen your ATO is going to try and make up the difference, and that is no good for water chemistry or your overall water level in the tank.

The only way I see you being able to do this is if you had an extra drain setup just above the normal water level of the tank, that could take on the extra water. Even then there will be a point where the water level in the return pump chamber of your sump drops. That would then suggest that you need something to turn off your ATO while your sump may be in flux. You might be able to control the ATO and the flow rate of your return pump with a controller, but you will still need that extra emergency drain to accommodate the extra flow, the last thing you want to do is run your return dry or flood your DT.

 

[Mike in CT]

If you really want to do it that way, put your ATO on a timer so it won't kick in during the times you increase the flow.

 

[Reflective]

Thanks for the replies. I definitely wasn't noticing the water level in the tank change, but my return section is pretty small compared to my tank, so my biggest concern was all the fresh water trying to get dumped in there. I'll change it to be a constant speed. I need to work with my Gyre more I guess, just none of my corals seem to like it much over 30% since it blasts certain areas, while my return is much more evenly spread around the tank when I blast it.