Solution for silencing overflor!

I've been meaning to post this for a while now because it works so well and want to share it!

I have a 180 gal tank and water a sump, and like a lot of people I did not want to drill it. So I got a CPR over flow. I think it was the CS150 it has a single 1.5" drain and was rated a little too high which can actually cause problems, noise. Flow rate of coarse was just fine it could handle anything my Iwaki 55 could put out. But I struggled to get it quite down. I used a dursao type setup and got it pretty dialed in but not enough for a living room tank.

I had seen a lot of the Herbie/ beananiamle full siphon setups but still did not want to drill the tank. So I bought the CS102 has two 1" drains. Now the rating for this overflow is closer to my pump output which will make it easier to keep quite because there will be less air mixing with the water. For a typical setup though the flow rate for this overflow paired with my pump is too close for my personal safety factor.

I put a valve on one of the drains and have no stand pipe on it. The other pipe is a straight shot with a durso type stand pipe. So I used the full siphon idea here. With the valve full open it devolves full siphon but out runs the flow and you get the flushing sound. So I restrict the valve a small amounts at a time until the overflow box fills with water and trickles down the second stand pipe. So now I get the silence of the Herbie style overflow without drilling.

The full siphon can handle almost the full volume of the pump meaning the overflow box can flow faster then the rating given increasing my softer factor. There still is a restriction of the front skimmer into the box so you can only increase the flow by so much.

Hope this helps others out there wanting a silent tank without having to drill!

It's a CPR over flow so it is a box style overflow. The half that is outside the tank has two 1" lines going to the sump.

One line is a full siphon and the other line has a small trickle. It is almost impossible to get the one line to have a full siphon balanced with the pump. So you have two options.

1 have it out run the pump and cause a flushing sound, safer but noisy and defeats the purpose here.

2 have it just under the output of the pump so the second line has just a trickle going through it that makes almost no noise.

If the first line plugs or something weird then the second line will take over and developed a full siphon and outrun the pump causing a flushing sound but this the emergency situation.