mr.wilson
.Registered Member
<a href=showthread.php?s=&postid=10452347#post10452347 target=_blank>Originally posted</a> by Insane Reefer
How much do you sell those for, lol.
Plumbing is not something I'm good at...
I can give you some more detailed instructions if it helps.
A 4" overflow may sound small, but that's just the trade name. It's a nominal 4". The actual outside diameter is 5.25", but the circumference is 18". An 18" overflow is quite desirable for a 65 gallon tank, especially if it's invisible.
I lost half of the surface area by locating it at the end of the tank, buried in cement, but my flow-through is only about 600 GPH. I typically locate them in the centre of the tank on a standpipe running through the bottom of the tank. I've also run them at the back of tanks with a couple of 45 degree elbows to bring the water back.
This one is freestanding, surrounded by live rock and drains a little over 1000 GPH per hour.


Here it is after 6 months, covered in coraline algae. You can see the 1/4" gap teeth overflow once they get a little slime.

This one is also freestanding and drains about the same amount. The only sound is a gentle trickle as the water drops 2" into the centre drain. This however, can be rectified by raising the centre drain for a smoother 3/4" drop.


Standard acrylic overflows aren't bad, but they aren't easily adapted to existing tanks. Acrylic doesn't bond well to glass, so you should always use a standpipe as a fail-safe. If the box leaks (within the tank) the drain point remains at the top of the PVC standpipe, and not at the point that the box leaks (in the event of the pump turning off). The wasted space in an acrylic overflow box is an excellent place to grow aiptasia, majano, xenia, or yellow polyps for biological/mechanical filtration (assimilation). They quickly remove excess food that bypasses the display tank. This tank has aiptasia in the two overflows with only diffused light.

This overflow is 4' high and is being used as a RDSB (remote deep sand bed). I was able to fit 15 gallons of sand in there. The water drains too quickly for detritus to settle, it's dark, and it's certainly deep enough. This one has three 1.5" drains, with the same Stockman modification. The water only falls an inch, so it's dead silent. The tube in the foreground is a breather/feeder/dissolved oxygen sampling access point.

You can see it at the far right, before the cabinetry was installed.
