Interest return pump phenomena?

[MONTANTK]

This has happened to me twice now and I’m sure it’s not a coincidence but I’m wondering if anyone has an answer.

Over the summer I set up a Fiji Cube 10g and it came with a basic return pump. I noticed that if I overfilled the third chamber, the pump wouldn’t restart and I’d have to disassemble it. I contacted Fiji cube and they sent me a new pump and I haven’t had an issue since. Figured it was just a bad pump.

Fast forward to this morning, I had to turn off my ATO on a different tank because the reservoir was low. I fill it up a little higher than normal and when I turn it on, boom nothing happens. I figure the pump somehow died overnight. I take some water out of the reservoir and like clock work the ATO pump kicks on without me fiddling with it.

Is there anything that can explain this?

 

[Ron Reefman]

Just a coincidence. Water depth differences that small shouldn't make that kind of an issue IMHO.

 

[MONTANTK]

Just a coincidence. Water depth differences that small shouldn't make that kind of an issue IMHO.

I didn’t try it with the ATO pump because it wouldn’t be possible but it was just so bizarre to me that I could take the first pump out of water and it would work fine and then I place it back in water and it wouldn’t start up. I was wondering if maybe it was some kind of impeller issue

 

[Ron Reefman]

Pumps have a wide variety of failure modes. Some are permanent and some are very transitory. I have a Fuji aio system and the little pump sometimes seems to 'bind up' and start to make a 'rattle' like noise. I pull the pump, rinse it in the kitchen sink and put it back and it runs fine for a month or two. That's why my newer aio tank has a Tenacor aio insert. It uses 4: filter socks and bigger pumps fit. I have a 900gph return pump and it runs at the lowest speed and seems to work just fine.