!@#$ bubbles from return pump!

[wonk]

I'm freshwater testing my 120 setup w/ basement sump. I can't figure out where my small but steady stream of bubbles from the return pump are coming from.

picure of my basement sump w/ freshwater in it:



There aren't any bubbles making it from the far side to the return inlet. You can see the mega Sequence 4300 pump with the 1.5" input and 1.5" line running up. There is about 14' of head on the pump. There are no water leaks. I just put silicone on all of the glue joints to see if something there was sucking.

I'm a little suspicious that maybe the ginormous pump is pulling the bubbles out of solution?? I don't understand the physics involved, but the pump is large and has 'only' 1.5 input. It doesn't make sense to me that if sequence spec's a 1.5 inlet that that could be the problem because then their pumps would always cause bubble issues...

I've heard that powerful pumps can somehow pull bubbles out of solution if they are restricted on the input side.

I am not dialing the flow back at all on the output side. The flow not going to the display is going right back into the sump.

HELP!!!

thanks
Kevin

[Fred_J]

I was going to suggest that before reading the second half of your post.

[mg426]

Try putting one of those prefilter pads on the suction side of your pump, see if that helps. It helped me big time with the same problem. You just have to keep it clean.

[wonk]

did you see bubbles in your sump prior to adding the prefilter?

[Scuba_Dave]

I had bubbles on my 125g when I 1st set it up with Iwaki 70 ~1450gph

It turned out there was a very small leak BEFORE the pump inlet. This was sucking air in, but when the pump was off, air would not leak out
Took apart threaded part - resealed, added glue to glued connections, problem solved

[wonk]

so the leak was from the threads?

thx

[zemuron114]

im actually going through this now as well...
i have a sequence 4300 as well feeding 5 55 gallon tanks. 4 with a 1" bulkhead and 1 with a 1.5

Im completely against glueing things because i hate the "final" aspect of it.. but i glued 90% of it.. i may have to glue it all... i will try the sponge over the intake.. But it is overpowered even for my 5 tanks.. i need to add my 3 more.. and i still think it will be overpowered!!

I would suggest to you, glueing everything again (drain the water from the pipes and let dry for a few days then glue.
maybe that will help?

[wonk]

thanks for the help. I'm blown away by how powerful the sequence 4300 is. It's really a totally different kind of pump to deal with than I'm used to. Super high quality.

I've already put silicone over all my glue joints to fill any holes.

Let me know how your sponge adventures go. . .