DIY PVC overflow, size question 20g

[drew4452862]

http://www.youtube.com/watch?v=65yVr7DiDls

This is going to be the overflow for a 20g tank ~1ft above the waterline of a 55g sump. Any ideas on the size of the pipe (ie 1/2")? Would I be better off just using a valve?

Thanks for taking a look!

[uncleof6]

These devices do not work out well at all. You need to figure your flow for the total system volume, and the flow rate will come out in a range in which this type of overflow will not work well.

The overflow needs to accomplish one thing: Surface skimming. This means the inlets to the "drain" system (this is not an overflow) need to be at the surface of the water, to perform surface skimming. Set in this manner, unless the flow rate is extremely low, the drain will suck in excessive air, and cause you problems. If the inlets are set so the drain does not suck in air, it will not perform any surface skimming.

The turbulence inside a 1/2" drain device such as this.... would make it useless. A 1" pvc drain such as this, would maybe flow 50 gph, without making you crazy.

There are many videos and threads concerning these devices and some variations, however, these things do not work as advertised. You would be far ahead, to use an HOB overflow, though even these have some problems.

http://reefcentral.com/forums/showthread.php?t=2202870&highlight=overflow

http://reefcentral.com/forums/showthread.php?t=2204426&highlight=overflow

For the record, I would make the 55 the display tank, and the 20 a sump......