Need advice and input on hole for overflow box

[Prime]

Hi.
First time posting here.

I'm looking for some advice on my overflow set up before I drill holes.
I'm setting it up as a ghost overflow style weir and BeAnAnimal drains.

Mainly I'm wondering if these holes are low enough and if I have enough holes connecting the inside box to the outside box.
I am probably going to spread the connecting holes further apart, most likely evenly spaced along the box, I didn't think of doing this until after I finished the drawing.

Also, the hight of the wier in relation to the holes and the top of the tank, is 25mm from the bottom of the euro brace enough or too much? the euro brace will be 20mm thick.

One other thing, teeth or no teeth on the wier?

Anything else I have overlooked?

 

[NanoReefWanabe]

Personally I would add an extra hole. I also would not drill for the returns, as it is just an extra point of failure (tank and potential leak)
The holes need to be one diameter from any edge...so a 1.5" bulkhead requires a 2"ish hole so you need to be minimum 2"" from edge of tank to edge of hole.
And no teeth, they are basically pointless, unless your goal with them is to reduce surface skimming ability by half... if the wier is designed right the water going over the top should be paper thin and no fish will surf that, a screen over the holes will stop snails from getting into your pipes

 

[Prime]

Hey.
Thanks for the input.
Just a few questions.
If not drilling for the returns, how would you recommend to set up the returns, just have them go over the top?

All the holes are 35mm/1 3/8" to suit a 25mm/1" bulkheads, currently they are all at least 42mm/ 1 21/32' from the edges but might be a good idea to move the return holes a bit further in and down if I keep them, going on your example.

No teeth seem to be the most popular way to go so I think that is the way I'll go.

How do you think the height of the weir in relation to the bulkheads and also the bottom of the bracing is.
Going off of a local Marine FB page I also asked on, most people are saying their display height is up to 10mm above the weir.
So going off of that I'm thinking of moving the weir height down 10 to 20mm and the drain holes to match or maybe a little more.

 

[NanoReefWanabe]

The wier height(water over the top) is determined by follow and size, too much flow over too small a box leads to deep weir height...turn the flow down and adjust the height of the pipes in the overflow box to reduce noise and wier height... or make the internal box bigger.

Yes I would run the return over the top... way less problems, no leaking bulkhead, no cracked glass, no 10g siphon from low return (go by the bottom of the bulkhead for siphon not where your pipe runs to, as the bulkhead could leak) also I wouldn't bother with splitting the return line, that has never made sense to me though... the idea of a return is to put clean water back in the tank, not create flow.

I thought the holes where a touch bigger for my 1" bulkheads I just drilled but yes they are 35mm too. So at 42mm you are good.

Not sure what bracing you are talking about, but if you are referring to the black trim on the top of the tank, then you want your internal wier to sit directly below it, ie touching the bottom side. And your external overflow box should be level with the top of it/tank. Depending on how you are building your boxes, this requires you to sometimes cut the trim out of the way... if you are building a glas set of boxes then you will likely need to cut the trim... if they are acrylic then you likely don't have too.

 

[Prime]

Hi.
The bracing is a euro style brace, the lowest part of it is 20mm from the very top of the glass and it is 65mm wide.
This is partly why I was drilling for the returns as going over the top would be pretty bulky although still doable, would allow for a full-width weir then too.

I'll attach a few pics of the revised design, I have left the returns in at this stage until I figure out how I'll do it.

Sounds like you have had issues with bulkheads and drilled glass?

 

[Prime]

Few more pics

 

[NanoReefWanabe]

I have seen many people drill the euro brace for the return

 

[Prime]

That's an idea. I'll have to see if the bulkheads will fit in them.
It's a double euro brace setup, designed to hold the screen/lids if I end up using them.
The top layer is 50mm/2" and the bottom layer is 65mm/2"9/16 wide, could be a squeeze but might work. I have been doing some looking around and from what I can find most of the glass cracking from holes is fairly thin glass.