Micro Bubbles!

[network13]

After installing a new little giant pump I am plagued with micro bubbles so bad I can hardly see the back of the tank. I have the pump pulling over the edge of the sump to the pump plumbed externally through 1" PCV, from there I have 3/4"ID clear hose to a SCWD and dual 3/4" outs. Where do the micro bubbles come from? Pump cavitation? I tightened the hose clamps on the clear hose to barb connections so tight I think there about to break.
On a good note though, with the former internal pump my temps were running a best low of 80 now with only one fan instead of two I am at a consistent 77.

Any help or suggestions on how to loose the snow storm in my tank would be greatly appreciated.

 

[farmboy]

You say you are drawing water (suction side of pump) over the side of the sump? Is this the same setup as the old pump?
If the inlet is very close to the surface of the water it will do this. It doesn't actually have to be out of the water to suck air from the surface.
Is your inlet in the same chamber as the drain from the main tank? The water falling into the sump makes a lot of bubbles.
If your water enters a different chamber, then falls into the sump area, it shouldn't fall more than 1 - 2 inches or this will cause additional bubbles. (add water to a safe maximum level--remember power outages)
I ramble but maybe this will help.

 

[robchuck]

When you plumbed the hook over the side of the sump, did you incorporate a way to prime the pump? It's more than likely that the pump has air built up in the impeller chamber and is cavitating.
Another possibility is a micro-leak where your tubing meets the hose barbs pulling in air, yet not leaking any water (kind of like the Venturi effect).
Finally, check the volute on the pump. I've had two LG pumps come from the factory where the volute wasn't on firmly and eventually started to show some salt creep at the pump accompanied by micro bubbles in the tank. A quick reseating of the volute in both instances was enough to stop both problems.

 

[bang guy]

Looks like you've got some good advise already. To test for cavitation just partially close the valve on the output side of the pump. If it's cavitation then the backpressure will make it stop. A siphon type setup with a small flexible hose is the perfect setup to cause cavitation. That type of setup restricts the input to the pump too much. If you can't drill a hole and use a bulkhead fitting then you need to use a much larger diameter rigid plumbing like 1.5" - 2" and then reduce it at the pump.
77F is pretty chilly for reef animals IMO.

 

[network13]

OK what is a volute? it that the same as the impeller chamber? if so then yes it was a bit loose so i tightened the wing nuts as tight as I could with my hands. I re-plumed both the intake and out flow sides. I ran 1.25" intake, and yes I did incorrperate a T at the top with a screw on cap to prime the pump. I teflon taped the threads before tightening it. On the outflow side I stayed with the 3/4", since the SCWD locked up on me I took it out of the picture. I did see a lot of bubbles coming from the SCWD before I took it out. I added a T and ball valve so I can taper off the pumps flow, since it is not going through the SCWD its a bit to much for my tank now. I had to take out the pre-filter sponges from my overflow boxes to keep from outflowing them and overflowing the tank. Now all the fish are hiding in the rocks and wont come out unless I power off the pump. I am thinking about spliting the return to both sides of the tank and then to dual spouts under water in different directions. So instead of one full blast I can split it in 4 directions. But what should I do about these darn bubbles? If it is air trapped in the pump, surely it would have worked its way out by now. right?

 

[slock]

my SCWD is causing a lot of micro bubbles, I've turned down the pump with a ball valve, checked and retightened all the hose clamps. Seems like a big burst of bubbles, then two cycles with a little, then back to a big burst. Love the idea of the thing, but if I can't get the micro bubbles to stop it's coming out.