Pump randomly losing efficiency?

[Vhuang168]

I too think it is a drain issue.

 

[Srt4eric]

So the gate is at full siphon and the other takes just a trickle?

I'm prettys sure he only has one drain plus the emergency drain.

 

[IOnceWasLegend]

I'm prettys sure he only has one drain plus the emergency drain.

You would be correct.

 

[Coral reefer]

I'm prettys sure he only has one drain plus the emergency drain.

That’s what I mean. One I would use gate valve to create siphon. The other I would use as the backup. If not tuned tight level could be going up in tank until one or the other forms a siphon and then drains excess water into the sump which slowly gets pumped back into display until a siphon happens again. Probably not what’s happening. Just a thought.

 

[IOnceWasLegend]

@Vhuang168 @Coral reefer So, I think both of us were right. Noticed water in overflow box rising today, then the alarm went off about an hour later. The water in overflow box was back to its normal level, and I watched the sump water level restabilize itself.

Any tips on how I could avoid a siphon like that forming so I can actually trust my ATO?

 

[JVU]

Unfortunately for you if it isn’t plumbed that way, the best fix is to have 3 drainpipes. First pipe is set to be always-siphoning with a valve. Second pipe gets just a tiny trickle of whatever is left over after the first. Third is a true emergency drain, in case of failure/clogging of the others.

Second best is probably to do the same but just without the third pipe, the emergency drain. Set the first drain to be barely always-siphoning with the valve, so that it doesn’t periodically go in and out of siphon.

Third best is probably to get rid of #1 drain above by opening your first valve all the way so that it takes all the water and the second pipe is the emergency. Safer but noisier. Will have a lower water level in the overflow.

 

[IOnceWasLegend]

Unfortunately for you if it isn’t plumbed that way, the best fix is to have 3 drainpipes. First pipe is set to be always-siphoning with a valve. Second pipe gets just a tiny trickle of whatever is left over after the first. Third is a true emergency drain, in case of failure/clogging of the others.

Second best is probably to do the same but just without the third pipe, the emergency drain. Set the first drain to be barely always-siphoning with the valve, so that it doesn’t periodically go in and out of siphon.

Third best is probably to get rid of #1 drain above by opening your first valve all the way so that it takes all the water and the second pipe is the emergency. Safer but noisier. Will have a lower water level in the overflow.

Much obliged. I didn't realize the drain could form a siphon and, come to think of it, I think the new return pump hasn't had the 'trickle into the emergency stand pipe' level that I had originally to keep it silent. Thanks!