Ted_C's Custom 320 - Overflow Ideas

[Ted_C]

So - Here are my ideas for creating overflows for this beast of a tank. I spent all day sunday learning Sketchup and designing these overflows. I'd appreciate all thoughts and opinions.

The challenges with this were the manufacturer drilled the holes - and they are pretty far down the tank (9 3/4" to the bottom of a bulkhead to the top of the tank). So the internal overflow has to be pretty deep. I do have some concerns with "waterfall" noises - as the water will be dropping almost 8 inches to the midpoint of the bulkheads to drain into the external overflow.

Everything will be attached to the tank via bulkheads and gaskets. No need for silicone - so no worries about mis-matching glass to acrylic and the warping that may occur.

#1 (I call this the "no-weir"):

I'll use three of these across the six holes drilled in the tank. I will assemble them myself - since at this thickness - the bulkheads will need to be installed before being glued.

Features: 20 inches wide and around 1 5/8" thick. No Weir - so I'll use gutter guard or 1/4" screen to prevent critters from going over the overflow. Should provide excellent surface skimming across the entire width of the tank.

Parts list:
All acrylic should be black and should measure 5/16" thick.
3 x 10 "x 20"
3 x 9 5/16" x 20"
3 x 1" x 20"
6 x 1" x 9"

#2 Overflow with Weir (this probably looks familiar)

Again - I would need three of these - not assembled so I can drill the holes and install the bulkheads before gluing. I'll also be looking for vinyl covered magnets to hold the weirs in place.

Here's a more detailed description of the measurements of the weir (since its hard to see on the pic):
20" x 2 5/16"
Router Holes are a total of 1 1/2" long x 1/4" wide (the drawing shows 1 1/4" - but doesn't include the 1/8" radius of the ends of the cut)
Router holes should be 1/4" from the next router hole (edge to edge) or another way to say it is - 1/2" from center to center
Router holes measure 11/16" (to center of hole) from the right and left edges of the piece of acrylic.
Router holes measure 11/16" (to center of hole) from the bottom of the acrylic (edit - correction)
Router holes measure 11/16" (to center of hole) from the Top of the acrylic

Parts list - note that all the acrylic should be 5/16" and black.
3 x 2 5/8" x 20" weirs (edit - Correction)
3 x 1" x 19 3/8"

3 x 10" x 20"
3 x 7 3/8" x 20"
6 x 9 11/16" x 1"
3 x 1" x 20"

 

[CuzzA]

I assume you're going to run a bean drain so I wouldn't worry too much about the waterfall effect as the height of the drain pipe will be set high enough that the internal water levels will only be a few inches from the top of the weir.

I would however be concerned with the weight of the water in the external box. I would definitely not rely solely on the bulkheads to hold the external box. Instead you could extend the top plywood plate for your steel stand to act as a bracket to hold up the drains pipes. I'm curious why they drilled them so low. Mine are being drilled 4.5" from the top of the glass.

As far as the box itself, I would go with design number 2, but forget the teeth and simply just cut the lid short a 1/4"-1/2" above the weir. Since its removable you could start with a 1/4" and see if the water touches it when everything is up and running and simply cut it shorter if it is. The reason I suggest no teeth is because 3x 20" boxes totals 60 linear inches, by adding teeth you will cut that in half to 30 linear inches. That's not very good considering a 96" surface. On my build, which is very similar in design, I'll have 3x 24" boxes. The sides of the boxes will serve as part of the weir too. So my total surface skimming area will be approximately 81". Close enough to 96". I would have gone with a true C2C, but I want the 4x 3/4" Sea Swirls mounted directly to the back glass and not sticking out toward the center of the tank casting a shadow.

Hope this helps.

 

[CrazyEyes]

How far down are the holes?

 

[Ted_C]

How far down are the holes?

(9 3/4" to the bottom of a bulkhead to the top of the tank)

 

[ichthyman]

I would however be concerned with the weight of the water in the external box. I would definitely not rely solely on the bulkheads to hold the external box.

I've done this technique many times if common sense is followed there is no issue.

 

[Ted_C]

I've done this technique many times if common sense is followed there is no issue.

Maybe a general outline of some common sense best practices please? are you talking about a certain weight limit per bulkhead?

I'd estimate the external overflow will be 96" (L) x 10" (d) x 4" (W) - that could hold almost 15 gallons of water. While I'll probably keep the water height around 4 to 5 inches in there (around 8 gallons) - it could weigh anywhere from 70 to 100 pounds.

It'll me mostly flush with the back glass (I say mostly because I'll probably get some extra gaskets to have the glass sandwiched between the gaskets) - so any torsional stresses should be handled by the planned bracing inside the external box and the contact with the full face of the glass.

 

[CuzzA]

I've done this technique many times if common sense is followed there is no issue.

I haven't.

Just seemed like a lot of weight in theory, but I've never calculated the physics.

Ted, you could shed some weight from the external box by just going bulkhead to bulkhead instead of the full 96". And like I said if you extend the plywood to support your pipes I would think that would be good. I've seen others use pvc pipe as a support too. Basically just cut a 1.5-2" piece of pipe and place it in between the bottom of the box and the top of the plywood. I would get an extra gasket too and cut it up as a spacer in between the box and the glass. Although come to think of it because your holes are at the bottom of the box they likely won't be trying to push in like they would if they were at the top of the box. Perhaps that was intentional by the Ichthyman.

 

[Ted_C]

Apparently, 5/16" thick acrylic (0.3125") is not readily available - I'll re-do my plans for 1/4" acrylic having learned this.

 

[Ted_C]

as it turns out - 5/16 is a size of acrylic that no one seems to carry

Re-draw my plans for 1/4"

If anyone would like the sketup templates for these - PM me your email address and I'll send them to you. Note: Sketchup2015 is only a 30 day free trial and the license fee is outrageous.

 

[CuzzA]

Sticking with the teeth huh? 30 inches isn't a lot. Not sure how much flow you plan on putting through them, but you could end up with a 1/2" to 3/4" rise, not very effective surface skimming if you're pulling water below the surface. If I recall you are using sea swirls so you'll likely have a lot of turnover from the sump. I would ditch the teeth, but to each his own. Good luck.