Design Questions: 120 Gallon Custom Rimless

[magnetar68]

I am in the early stages of planning the upgrade to my current Red Sea MAX 130D. This is a long term project because I will need to save for it. But I am considering a Toothless Calfo/Coast-to-Coast type overflow (not sure if there is a difference between these two designs): I have been told these can be very quiet when combined with a BeanAnimal overflow design. Quiet is my most important design constraint. I am planning on being able to support SPS corals in this tank, so I do need considerable water flow. Is about 900gph OK?

I am new to aquarium design and I am reading a lot on the internet which is no doubt inaccurate, but here is the design I am interested in and some questions I have:

• 48”x24”x24” Rimless Tank
  • Is 1/2" thick enough?
  • Because of the overflow design, the top ~1.5” or so won’t hold water
  • Starphire Front
  • Black back
• Coast-to-Coast Overflow
  • How long does this need to be?
    • Maybe 42” of the 48” leaving 3” on each side? – room for the return 1” notches
  • I think the idea is that you tune the drains to take a very thin sheet of water over this edge (gate valve not shown)
  • Does this edge need a bevel shape? (I think this edge needs to be shaped a little to get a clean flow over it).
• External Overflow box
  • The plan is a BeanAnimal Safe and Slient overflow.
  • What size drain pipes? Is 1.5" too big for a 120 gallon?
  • The design goal with the external overflow box is that the drain pipes will go straight down into a sump input chamber with no elbows to turns.
  • I assume 1/4” thick is OK for just the external box?
  • How deep and high does it need to be?
  • How far apart do the three holes for bulkheads need to be to fit 1.5” PVC?
• Return
  • What size return? Is 1" too big?
  • I am thinking about two notches for the 1” return J-tubes to sit in
    • I could just have the return tube go over the top, but I am thinking these notches will provide a cleaner look
    • I show these as square notches, but they could be round to nicely fit the return tube.
• Closed Loop Circulation (not shown)
  • I may want two holes drilled into the back for a closed loop circulation system. Will I need this system? I am planning on Vortech pumps for water movement.

[dogstar74]

I don't like the notch, IT would weaken the material on the back. I would rather a bulkhead fitting. Or just take the pipe up over the top. It's not that much of an eyesore. Plus any waves in the tank would probably reach that high, so you'd fight endless salt creep down the back of the tank.

I suppose you could do it this way, but it's the first I've ever seen notches like that cut into the back pane.
Cheers,
Aaron

[NanoReefWanabe]

the notch is the best and cleanest way to do it if the tank is being built from scratch, however the corners of the notch cannot be squared they must be rounded, and you overflow box has to be the same overall height as the rest of the tank...other then that i love the design...i would not notch the returns into the top of the tank though, seems pointless to me, all that will do is create a very weak point in the glass and lower your water level in the tank.

only thing i really see is 48x24x24, is hardly a custom tank as that is what all 120 are...i suppose the front in starphire is nice and rimless always looks nice but the cost to build such a tank is going to be 5x what a standard 120 would cost...

as for the glass thickness, no, 1/2" will not be enough, standard 120 is half inch and uses a top and bottom trim with a brace, i am betting (though i dont have a tank calculator) you would need 15mm glass for the sides and 19mm for the bottom for it to be rimless...and you would still likely need a eurobrace around the bottom of the tank...

[magnetar68]

OK, forget about the notches. I am more interested in the required dimensions. I found a calculator here that says I need 1/2" (0.47in) for the sides and back and 3/4" (0.63in) for the bottom with a safety factor of 3.8 which is recommended for rimless aquariums. It also says that 1/4" is OK for the external overflow. I still need some suggestions on the the external overflow. In the updated design below, I am showing the overflow 2" from the top and 6.26" tall and 4.25" deep. Is that enough room to deal with the plumping? Also, is 1.5" drains and 1.0" returns too much or OK?

The design also shows the concept of an L shaped sump I am considering to ensure the drain pipes go straight down with no bends (forget about the specifics of the sump, I just grabbed a random sump and modified it; the point is the concept of an L shaped sump).

[dvups1]

can you provide a source for the calculator you are using? 3.8 is the safety factor for braced tanks. I would think a rimless would need a higher safety factor.

[blackizzz]

Most Rimless glass calculators uses 7.6 as safety factor, it needs to be that much higher (or close) or it will bow...

HTH blackizzz

[magnetar68]

Thanks for the info. The calculator did not actually say 3.8 for a rimless. I was unclear. You type in the safety factor you want, and then it calculates the size of the glass. I read another post somewhere that talked about 3.8. As I stated in my intro, I am gathering info so in the process of learning. It makes sense that a rimless would want a higher safety factor. At a safety factor of 7.6, here is what it comes up (and here is the calculator):

Recommendations
Glass Side/Back/Front 0.67 in
Glass S/B/F Deflection 0.01 in
Glass Bottom Thickness 0.89 in
Glass Bottom Deflection 0.00 in

Since my original post, I have approached a few vendors about building this tank, and most have said they will not build a rimless aquarium with an external overflow hanging on the back. Additionally, some have said they will not build a rimless with a height higher than 20".

There are two general compromises that have been proposed. One is to use an internal coast-to-coast overflow if I want the tank to be rimless. To keep the overflow external, vendors have recommended to Eurobrace the top and make a "trimless" tank rather than a rimless one.

Does anyone know the suggested safety factor for a eurobraced aquarium? Does it go back to the 3.8 number? If so, here is the recommended glass:


Recommendations
Glass Side/Back/Front 0.47 in
Glass S/B/F Deflection 0.02 in
Glass Bottom Thickness 0.63 in
Glass Bottom Deflection 0.01 in