Overflow Help

rbeirne · Aquarist Joined: 09 Jan 2004 Posts: 13

I purchased your 800 gph model overflow and it wasn't enough flow for the 785 gph Quiet One 3000 pump :x So I had to return it. I guess I've got to get a larger model and have a few questions.

1) I only have a single vacuume line that drains to a single sock filter. Is it possible to have a dual overflow drain to a single vacuume hose or does this reduce the flow to what a single overflow unit would do, 800 gph?

2) I was looking at the CS-150. At 1600 gph this should be plenty of flow right? How much space behind the tank is necessary for this overflow? I only have 5.5".

3) The CS-150 has a 1.5" bulkhead. Does 1" PVC slip into here?

Support · Posted: Mon Jun 26, 2006 9:25 am Post subject:

The CS100 will flow enough water to keep up with the QO3000. How high was the water level in the overflow box while running?

Two overflow drains can be combined into a tee but this will slow down the flow rate. You can tee into 1 1/2" or 2" tubing and will restrict the flow less, but will not perform at 1200 gph. What flow rate are you trying to obtain?

The CS150 measures 6 1/8" behind the tank, so this will not fit unless you can move the tank from the wall. This overflow has a 1 1/2" ID bulkhead that uses 1.5" OD PVC piping.

rbeirne · Aquarist Joined: 09 Jan 2004 Posts: 13

From what I remember I thought the water level in the overflow box was unusually low. However, these boxes are different than the U tube design overflows I have always used. What do you think?

Support · Posted: Mon Jun 26, 2006 3:00 pm Post subject:

The water level in the back will be determined by the return pump. The higher flow rate will result in a higher water level inside the overflow box behind the tank. The water level can be 1" from the bottom to right above the prefilter sponge. Any level around there will be fine.

rodin58 · Aquarist Joined: 21 Jan 2007 Posts: 9

I disagree with the "support" reply. I have a 150 rated at 1600 gph and a iwaki pump rated at 1100 gph and I had to put a ball valve in to slow the return. my 150 would not get more than 1 in. of water in the back tank and my aquarium would have over flowed if I had not put the ball valve in. I have very little restriction coming out of my overflow box, just one 45 to get it under my tank and into my sump. The box is also sitting flat on the tank and it will not take anymore water. I asked about this in another thread but havent gotten any replies...only links to porn sites...can't we clean this up?

Support · Posted: Mon Jan 22, 2007 9:49 am Post subject:

Be sure all the air is purged from the inside of the overflow box. Are you running an Aqua Lifter or venturi pump with the overflow? What size tubing do you have between the overflow and the sump? If you plumbed the overflow with less than 1 3/4" tubing, the flow rate will be reuced through the bulkhead.

If the water level is low in the back of the box, the return pump should not have to be restricted. Please make sure the overflow does not have any air pockets in the top channel.