[Lithium]

Hello all-
I have a 100g tank with 1 corner overflow and a large sump with a baffle system. I plumbed the tank with PVC tubing and used 3/4" from the main pump back to the tank and 1" to collect water in the overflow. The piece of tubing delivering water from the bottom of the tank under the overflow to the sump below is 3/4". I seem to be having a hard time adjusting the flow so that it is well balanced between the overflow and the sump chamber where the main pump is.

One of two things happens:
1) The vertical pipe in the overflow (which has no holes drilled it but only collects water from the opening at the top, about 2" below the level of the water spill) sucks up a lot of air and is very noisy. The air bubbles below into the sump. The water flow is fine like this in that it stays constant but the overflow is very loud.
2) I tried a "Durso standpipe" approach (www.dursostandpipes.com to see a picture). I tried this with two different sizes for the submerged intake:
a) 1":This results in water flowing very fast (but also very quietly, no air) down to the level of the submerged intake and then it starts slurping loudly.
b) 3/4" matched to the size of the rest of the tubing (it is actually a bit smaller due to the 90 deg turn) works great but does not drain fast enough and the main pump goes dry.

What shall I do: match the size of the pipe in the overflow (3/4")? with or without durso system? get a less powerful pump? Please help! Thx!!!

[jvharding]

I had this same problem in my tank. I am Pumping 1200GPH thru 3/4" into my tank and return in 1" PVC. In my bulk head entering my sump I screrwed 3/4" to 1/2' It was an attachment to my RIO Powerhead. My pressure entering the sump has increased thank goodness for the cap keeping water in. and all my gurgling went away. By the way I am using Classic Stand pipe with Holes and No Sponge!

[jvharding]

I no longer use the ball valve to adjust flow! Do you have a ball valve?

[Lithium]

I was able to solve the sucking problem completely by reading a bit more carefully about Dursos. The top vertical portion needs to be capped (with a threaded PVC plug in my case) and then gently vented. I drilled two holes in the plug and fitted them with airline (one was not enough). Works like a charm. Still quite a bit of gurgling into the sump, but not too bad.

Now I wish I could find a quieter return pump. My Rio 3100 causes quite a bit of vibration and it's a constant humming in my small living room. Are Rios known to be noisy? Can anybody recommend a quiet pump?

[Lithium]

Oh and yes, the flow valves are both fully open...none of that "sweet spot" nonsense that just does not work.

[jvharding]

I Use BlueLine pumps on my tank but i hear that the Iwaki pump is much cooler. these are External Pumps.

[fish dad]

try sticking a peice of flexable tubing down inside overflow on the drain side.only needs to be in deep enough to stop gurgling.acts as a vent to brake suction.hope this helps.