Drill tank or overflow box?

[thepuffah]

Since I am getting my 180 soon, I am wondering if I should pay my LFS to drill 1.75" holes in the back of the tank, or just buy an overflow box. If I did drill, I would have the holes where the water level would be. So in a power outage the water would go below the bulkheads. Here is a diagram:



The top left are the in-flow bulkheads and the 2 in the middle are the returns. Which leads me to my next question... should I have the return lines go above the tank, like a hang over tank tube. Or keep it how it is on the diagram, and put a check valve on there? Thanks!

[seaham358]

I would drill, IMO a much better way to go. Both my tanks are drilled and both refugiums and I never had a flooding issue. I have the return over the top using a J hook made by amiracle. Nice and easy return hook up. This way I get good flow through the tank and have movement on the surface without using any power heads.
You may want to have some of the flow going to the fuge T off and have some go to the sump. a 1 3/4 over flow will be too much flow in a fuge IMO.
you can go with the center returns but with the tank packed with LR it will interfere with the flow and using check valve is just one more thing to go wrong. JMO..

[Macrosill]

If you are getting the 180 new the just order one predrilled. Otherwise drilling the back of the tank ,imo, is better than a hob overflow. However the bulkhead placement is not the determinign factor as to whether a tank will siphon out and overflow the sump in a power outage. This effect is prevented with the design of a standpipe. It is designed like an upside down U and the water level can only get as low as the bottom of the U in the worst case scenario. Check out www.dursostandpipes.com that is the one I have. Also keep in mind tha return nozzles should be faily shallow, otherwise they could perform a siphon and suck out the water if for some reason the flow gets reversed when the power goes out. IMO a check valve could be useful. They are a simple rubber flapper design that closes when the water flow reverses. Used in plumbing all the time and have a very low failure rate. It depends on how worried you are about a flood.


Good Luck,
Brian

[thepuffah]

I decided that a HOB overflow would just be easier for me. Now, if I got one that can do lets say 1200 gph, could I put a ball valve on 1 of the 1 stand pipes? So I can limit flow on the drain going to my fige and have the rest of the flow go into the drain that goes into the sump? Or do you know where can get an overflow box that can go 1200gph or more with only 1 bulkhead?

[jasno999]

I am a little confused by the diagram yo uhave posted. Probably jsut me but I don't get the tubes goign into fuge. I would think you want water out of the tank to go to the fuge, or partky to the fuge and partly to the sump. The fuge should then gravity feed into the sump and the sump shoudl pump all water back to the main tank.

Drilled is best cause then in a power failure (as long as you set it up right at thestart) you should not have any floodign issues. With a hang on overflow if you lose the syphion and the power comes back the pump from the sump will overfill the main tank and cause you a nice flood.