Beananinal overflow hole hights?

[raymond90]

Hi, im in the process of setting up a 6x2x2 tank and i'm at the stage of drilling the 3 holes for the over flow. Before i go and drill the holes can someone tell me how far from the top of the tank is the best hight to drill the holes for it to work?

I remeber reading somewhere that bean drilled his 4.25" to the center but he said that was because they were already drill there from his previous set up. However i cant find where i read that so i'm not sure if im imagining things.

I'm going to be using 1" bulkheads and 1.5" pipes from tank to sump and i will set the full syphon bulkhead 1/2" lower than the other 2.
My tank will be built into the wall so i can set the the framing to suit the water level which i assume is determind by the hight of the overflow box?

Sorry if this is a silly question but this will be my first setup with a sump and first time with a drilled tank so i just want some more advice before i possibly destroy a brand new tank. Also i know my glass is not tempered so drilling wont be a problem.

Many thanks,
Raymond

[autodave]

At least 1 hole diameter from top. So if your drilling a 45mm hole, your centerline should be 67.5mm

[raymond90]

Ah I see so it doesn't really matter how far down they are then? As long as they are far enough down so they don't effect the strength of the glass pannel they go through? I thought it might need to be a certain distance down for getting the syphon started?

[BamBam17]

Does that same rule of thumb apply to acrylic? I'd like to get as high as possible to minimize overflow box height

[autodave]

Originally Posted by raymond90

Ah I see so it doesn't really matter how far down they are then? As long as they are far enough down so they don't effect the strength of the glass pannel they go through? I thought it might need to be a certain distance down for getting the syphon started?

Are you doing a internal weir?

[raymond90]

Yea i am planning on using an internal weir box. It will be along the left hand side pain of the tank so i would like to make it as small as possible.

[raymond90]

by small as possible i mean depth and pretruding out in to the tank wise. the width will the full 2' width of the the tank

[autodave]

I would figure out the dimensions of your weir and how far down from the top your going to place it,I think alot of people put it 1"-1 1/4",which will determine the water level in your tank. Then center your bulkheads in the weir. May be this photo will give you an idea: http://reefcentral.com/forums/showpo...postcount=4509

[raymond90]

Thanks thats a great help think ive got it sussed now, however ive been doing some more reading and thinking about going with an external over flow and drilling a series of 1/2" holes about the 1 1/4" mark down from the top of the tank to act as the weir and having the bulkheads going through the bottom of the box like most of the other bean externals ive seen. This way i can have a bigger box so its easier to work in and it will be completely out of view.

For a 180g tank with external overflow would it be worth keeping all the pipes 1.5" or just keep it the same as beans origonal design of reducing to 1" inside the box?

[autodave]

You will still need an internal weir. I would stick to Bean's design unless your gonna put alot of flow through it

[raymond90]

so having a series of 1/2" holes drilled 1 1/4" from the top of the tank along the the width of the tank would not work as a weir?

[raymond90]

This is the the kind of setup im meaning. Do i still need an internal weir or do the holes act as a weir?

http://www.youtube.com/watch?v=Ufq3VnRCXK8

[Daimyo68]

The idea behind the weir is 2 fold: oxygen exchange and surface skimming.



While the design in the picture you provided will provide both, it won't be as efficient as the 24" weir you initially planned for.



What I would do, is drill 3 1" bulk head holes through the tank, and build an internal weir that only needs to be 1" wide into the tank. You then have the advantage of a true weir while not taking up much real estate in the tank.



Then go as planned on your external box on the back of the tank using 1.5" all the way. There's no reason to neck it down since you building from scratch. Bean used existing holes that were meant for 1" bulkheads.





Sent from my iPad using Tapatalk HD

[raymond90]

Something I maybe should have mentioned earlier is that this is for a freshwater tank, so is surface skimming as important in a freshwater setup? The reason I posted this in a reef forum is because this is where I first found out about the bean setup and because you guys really know your stuff and have great advice

[Daimyo68]

I would imagine surface skimming is good for fresh also, but I'll step aside for someone else to chime in on that.

[raymond90]

Hmm not sure wich way to with now, a 1" wier wouldn't look out of place in the tank but going with the holes/slots would also act as a strainer to stop fish getting into the overflow box. Think i prefer the holes/slots idea but would like the any input from anyone thats used them? Would it weaken the glass to much?

If only i could get acess to the back of the tank once its in i would just go with an internal coast to coast.

[zaraemna]

How about a horizontal slot almost as wide as the external overflow box.

[autodave]

Originally Posted by zaraemna

How about a horizontal slot almost as wide as the external overflow box.

That's how my tank is,my tank builder notches the back pane with a waterjet before assembly. Then a external overflow box is mounted.

[a.browning]

Originally Posted by Daimyo68

The idea behind the weir is 2 fold: oxygen exchange and surface skimming.



While the design in the picture you provided will provide both, it won't be as efficient as the 24" weir you initially planned for.



What I would do, is drill 3 1" bulk head holes through the tank, and build an internal weir that only needs to be 1" wide into the tank. You then have the advantage of a true weir while not taking up much real estate in the tank.



Then go as planned on your external box on the back of the tank using 1.5" all the way. There's no reason to neck it down since you building from scratch. Bean used existing holes that were meant for 1" bulkheads.





Sent from my iPad using Tapatalk HD

Exactly what I'm doing for my 75 build. Seems like the best option if you are not able to cut a slot in the back of your tank (or just don't want to). Here are a couple mock ups I made showing the design, not to scale but should give an idea at least.

Front

Back


The only reason I made the internal box go so far down was to hide the external box when viewing from the front. The external will need to be longer lengthwise than in the pics, to account for the plumbing.

[raymond90]

I like the idea of the horizontal slot although since i already have the tank unfortunately flow jetting is not an option, can i cut it with a diamond glass cutting disc in a drill or grinder maybe? I would be pretty confident cutting it my self if it can be done.

[Daimyo68]

That is how I designed my stand back in December. Checkout my 75g Album. Building it with the extended back leaves plenty of room under the stand with a 40B sump. You might want to extend the base where the tank sits. This will give you a support bracket for you pipes to go through.

Originally Posted by a.browning

Exactly what I'm doing for my 75 build. Seems like the best option if you are not able to cut a slot in the back of your tank (or just don't want to). Here are a couple mock ups I made showing the design, not to scale but should give an idea at least.

Front

Back


The only reason I made the internal box go so far down was to hide the external box when viewing from the front. The external will need to be longer lengthwise than in the pics, to account for the plumbing.

[a.browning]

Yep, that was my plan. Just hadn't gotten that far with the CAD drawing!