beginner overflow box questions

[jacksonpt]

I'm trying to get enough knowledge together to make my own overflow box. I want it to be triangular shapped so it will fit in the back corner of my 44g pent tank.
So, here come the novice questions...
1) Is there a prefered material to make the box out of? Acrylic, glass, plexi, ??? Main concerns would be price and ease to work with. What about adhesive? Silicone, sements, glues???
2) Most overflow boxes I've looked at have a box inside the tank to catch the overlfow and begin the syphon. They also have a box on the outside. Would it be possible to eliminate the outside box by running the siphon tubing straight from the overflow box to the sump?
3) I understand the relationship between water flow via the siphon FROM the tank and water flow from a return pump TO the tank. They have to be in sync to prevent tank/sump from overflowing. How can I determine/guestimate how much siphon flow I will have so I can make sure I get an appropriate return pump?
4) Is it possible to get a return pump that will provide enough current that I will no longer need powerheads? Is this realistic? From what I've read, sumps are more beneficial if the water movement within the sump is very slow. Wouldn't a stronger return pump increase the water movement within the sump? Would this limit the effectiveness of the sump?
This is what I'm thinking...

 

[joerdie]

imo
1.acrylic with silicone is best to use when building
2. you want a box on the outside for a few reasions mainly though you want the siphon to NOT break when the power goes out.
3. mose overflows are adjustable and you may need to make yours that way. the only other option that i know of is to be able to buy a pump that is too powerful and scale it back with a ball valve.
4. i am currently running a mag9.5 in my 150 reef and the water (at 3 feet of head) is blasting. i still have another pump in the tank though for water movement on the other end but you have a pentagon so im not sure about other pumps in you tank
I hope this helps!!!

 

[zafirablanca]

I have a store bought overflow, so I cant speak to the DIY plans. But I can tell you that jeordie is right about the siphon. You dont want to lose your siphon on the overflow if the power goes out.
It is a royal pain to re-prime these (saltwater doesn't taste to good ).
What you want to avoid is a 'back' siphon going down to your sump through your water return line if the power goes out. Once your pump stops, water will start to flow backward through your return line and through the pump and into the sump.
Most people drill a small hole at or just below the surface of the water on the return pipe where it discharges into the main tank. This is usually called a siphon break or anti-siphon hole. Once the water drops below this hole, air enters the pipe and breaks the siphon of water down to your sump. Under normal operation this will shoot out some water into your tank and ripple the surface (which is supposed to be beneficial anyway). You may also install a check valve along with the siphon break hole, but be sure it is the correct type (see the 'one way valve' thread for details).
I am currently trying to minimize/ eliminate powerheads in my tank also. I have a very powerful return pump that I have to trim back with a ball valve right now. I am trying to modify my set-up to use all of that pump power and avoid powerheads. I have something like a short vertical spraybar return in each of the back corners of my tank. These are oriented in a way that really move the water around. My limitation is my overflow boxes at the moment, but I think that I can fix them. Other people have come up with creative solutions to get around using powerheads too, just try a forum search and see what other threads you can read up on.
As to the flow in the sump, you can have it be a fast or slow as is necessary for the circulation that you want in your tank. Slow flow is good for a refugium. Some people install a refugium within their sump, and that would be where things can get tricky adjusting flow. The ideal set-up is to have a sump and a refugium in seperate tanks. This is what I have set up.
Fast water movement in the sump, with my skimmer, heater, baffles to minimize bubbles, and my return pump. Think sump = mechanical service to water quality. Slow movement in the refugium with deep sand bed and maybe LR rubble (for bio-filtration, waste eating critters, pods for fish food) and macro algae (for nitrogen removal, food for tangs). Think refugium = biological service to water.
Hope this helps.
Good luck,
-Christine