Overflow level fluctuating, why?
 

So, somewhat new 210 (I think) gallon custom tank 72*30*24. Been running since about Feb. New DCT-15000 return pump, external overflow, herbie drain.
Since day 1 the overflow level fluctuates & I can't keep it the same for more than a day; with minimal adjusting on the gate valve. I once had a Waveline pump cause this & changed it out, problem was solved. I changed out the pump only yesterday & still fluctuating. I have removed & cleaned out the gate valve a few weeks ago, there was really no build up in there. So my question is, could the Spears (bought brand new) gate valve be the problem, the return pump controller or power supply. I will change out the controller & power supply this weekend, incase there is something faulty there.
Any ideas where else the problem could be? Could I have missed any pertinent information? 1.5" drain & 1" dual return lines; I have the return pump running at about 7 out of 10 on the controller.

Throw a non-DC pump on there and see if the problem persists.

what difference would non-dc make??

I only ask because I'm looking at switching my AC pumps and now I am curious. Sorry to chime in on your thread without anything helpful

Unfortunately, no AC pumps nearby to try out, with that flowability.

No worries Brunz.

Most definitely the issue.

AC pumps run at a set constant speed, whereas DC pumps can fluctuate amperage (all by themselves), causing inconsistent flow.

Put something smaller on...as long as it's AC. It's just to check, doesn't have to be the right amount of flow.

Ian, I had same issue when using a controllable DC pump, mine was a waveline but use to get the same problem till I switch to an AC pump


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That's a good idea, will try an Aqueon A600 & see if that solves the issue.

Thanks Galizio, got one here to try this weekend.

I had that problem when I installed my vectra pump and set it to ramp up and down through the day. It would also off set my auto top off.
After I figgered that out still had problem with ato. Wine a week it would stop working. Then water would evaporate and not top off.
I had to put a price of cardboard between the magnet on the float. My glass was to thin.

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