DIY Overflow not working perfectly

worrballer

worrballer

Member
I built an overflow box to cover the bulkhead. Just like glass-holes but cheaper... but not as nice lol.
The box dimensions are 3x3x5 inches (LxWxH) with 1 1/4" teeth. Bulkhead is 1" I have airline tubing down the pipe and coming out of the tank side of the bulkhead.
Here are my problems with it:
Slight gurgling from the airline tube
No surface skimming
Doesn't seem to drain the water as fast as I thought (~300 gph)
I hope I described this well enough, if not I can clarify.
Water is level with the trim (where I want it). Also water level in the overflow is the same as out.

Here you can see the airline tube and level of water inside the overflow.

Back plumbing. The airline goes past the elbow down the pipe.
 
bmkj02

bmkj02

Member
IMO the drain line is too small. You can adjust your return line if you have a valve on it to slow it down to give it a chance to drain. What size tank do you have? Have you tried without the airline? You might have to drill another 1" drain next to that one or on the other side to drain better
 
worrballer

worrballer

Member
I have a ball valve on the return and it is turned back so the water stays level, just doesn't cascade into the overflow.
When I put pieces of acrylic on the box the water gets really close to overflowing and then levels out anyway.
The tank is stocked and I've already drained and moved livestock once. I'm trying to stay away from doing that again.
I heard elsewhere that drilling a hole in the elbow in the back might help. Smaller hole = higher flow.
 
bmkj02

bmkj02

Member
You can drill the elbow like you said. That usually the way I see them done anyways and see what happens. I still think the drain is too small though. It also can be the way you routed the drain line to the sump. It might be backing up at a 90 degree elbow. You can probably change it out to a hose to avoid the bends if that is the case or redo the pvc line.
 
worrballer

worrballer

Member
Well, there is only one elbow and I don't see a way around having that one. It is an elbow then straight pipe to the sump.
And if I open the ball valve on the return I'll have a flood.
So yesterday I cut the bottom two inches off the drain line and that didn't help. As a matter of fact, it made it worse.
When I get some time (I just had a baby girl so that might not happen for a long time lol) I'll drill the elbow with a small bit and see how that works.
 
scsinet

scsinet

Active Member
The reason you do not have any surface skimming is that you have overwhelmed the overflow box so as to prevent it.
The waterline should be right at the bottom of the teeth, not an inch or more above it like in your pictures. It has to "spill in" to the overflow box in order to achieve surface skimming. You've cranked your pump up to cause water to build up over and above the overflow box to a level that is desirable, but unfortunately, the only real way to fix this issue is to turn your flow down and raise the overflow box higher, so that surface skimming is acheived at the water level you want.
What kind of flow rate are you trying to achieve?
 
P

pelagic

Guest
If i were you, i'll take that big box out of the tank and save a lot of space and more light for your corals. It will cost around $12 and you could make it your own way. If you need 300gph , 3/4 inch pvc is your choice. I have 3 of them and they work like a charm. Need pictures or building plans. Let me know
 
You must log in or register to reply here.
Top