Neptune Cor-15 RPMs are always fluctuating...is this normal?

Z Burn's Reefing · Sep 12, 2023

Hey All,

I just upgraded to a Neptune Cor-15 as a return pump. I noticed the RPMs (running at 60%) are bouncing all over the place. I accepted small jumps here and there, but over the last 24 hours the RPM high has been 2210 and the low has been 2110...nearly a 100 rpm difference. Is this type of fluctuation normal? The pump is pretty darn clean, only a week old...do these pumps have greater stability if i turn it down some? Or perhaps turn it up? I was hoping for a return pump that was really tuneable and stable...kinda of disappointed...

Thanks for any thoughts and experiences for those who have run the Cor pumps.

gbru316 · Sep 12, 2023

I find mine does this too. I occasionally have to retune my overflow because of it.

Z Burn's Reefing · Sep 12, 2023

gbru316 said:
I find mine does this too. I occasionally have to retune my overflow because of it.

Thanks! Yea....I am running a red sea tank and the constant adjusting of the down flow value (which controls water level in the overflow) is tiresome. I was seeing the water level dip a little in the overflow and so I adjusted the downflow value, but perhaps if I let it ride, the pump will increase RPMs again and balance itself out. Today I dialed the pump down to 40% to see if stability is a little better at lower gph.

RoanokeReef · Jul 24, 2024

Z Burn's Reefing said:
Thanks! Yea....I am running a red sea tank and the constant adjusting of the down flow value (which controls water level in the overflow) is tiresome. I was seeing the water level dip a little in the overflow and so I adjusted the downflow value, but perhaps if I let it ride, the pump will increase RPMs again and balance itself out. Today I dialed the pump down to 40% to see if stability is a little better at lower gph.

Ever figure this out? Tired of changing it constantly.

piranhaman00 · Jul 24, 2024

Switch to Jebao , problem solved

Z Burn's Reefing · Jul 29, 2024

RoanokeReef said:
Ever figure this out? Tired of changing it constantly.

To be honest, if the pump has been recently cleaned, things are relatively stable...but a couple months of use and just a little bit of build up...it starts fluctuating again. So at the moment I just have to run a lot of citric acid baths every 2-3 months...not ideal. I have noticed a little bit better stability of flow if I turn the pump up...I've been running it at 60%.

RoanokeReef · Jul 30, 2024

Z Burn's Reefing said:
To be honest, if the pump has been recently cleaned, things are relatively stable...but a couple months of use and just a little bit of build up...it starts fluctuating again. So at the moment I just have to run a lot of citric acid baths every 2-3 months...not ideal. I have noticed a little bit better stability of flow if I turn the pump up...I've been running it at 60%.

I have to bump mine daily 2% to keep the speed up. What's strange is it's almost the exact same time each day ot slows down. I took it apart and it spotless. Working with Neptune so it will be interesting to see what they say. I love the extra features of the pump but it will soon be retired if they can't figure out what's going on.