External overflow box / opening dimensions advice needed!

Discussion in 'DIY' started by Jeremy, Jan 22, 2015.

  1. Jeremy

    Jeremy Guest

    Hey everybody,

    So I am just starting the planning of an approx. 34 gallon tank that I picked up from a guy about a year or so ago. Ive since relocated and am ready to begin this new system. It is a rimless tank with dimensions as follows: 24" wide x 18" deep x 18" tall x 1/4" thick. In order to maximize the amount of space available in the tank when finished, I want to install an external overflow box with a weir cut in to one of the long sides of the tank.

    This brings me to my first question. First off is what does everyone think would be a good size for the overflow box? I am thinking of making the external box around 18" long. This should leave me enough room on each side to drill for a 3/4" bulkhead to connect loc-line returns. If I do this, I'm thinking that my final dimensions would be 18" x 6" x 8" deep. I plan to make the external box out of either 1/4" or maybe 3/8" glass and will also put some triangle gussets under the box to help support the extra weight. Even with the gussets I still intend to use brackets to support the weight of the plumbing.

    Now for my other main question, what size does everyone recommend for the opening to the overflow? This will be my first rimless tank so I'm not sure if that will have a big bearing on the height of the opening or not though I assume it will. Another question is suggestions either for or against both having and not having teeth on the weir. I think that should do it for now though I'm sure there will be more questions later on!

    I look forward to any and all help/suggestions.

    Jeremy

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  2. Coral reefer

    Coral reefer President

    Def some sort of teeth or something to keep fish etc out of the overflow. Why glass over acrylic?
     
  3. Jeremy

    Jeremy Guest

    That's the way I was leaning also but have heard a lot lately about having no teeth also so wanted to get some opinions on both options.

    I'm planning on using glass because the tank is glass and have read that it's not a good idea to mix the two since silicone doesn't adhere well to acrylic.

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  4. rygh

    rygh Supporting Member

    I did not use teeth. Instead I rounded the overflow side, so you get laminar flow.
    Seems to help keep it slightly quieter.
    I used plastic gutter screen to keep the fish out.
     
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  5. Jeremy

    Jeremy Guest

    I'd be interested to see a pic of this if you have some. This sounds a lot like what I want to do. As for the screen, I was thinking either to use the gutter screen or maybe figuring a way to use the clear screen from brs.

    sent from my note 4
     
  6. rygh

    rygh Supporting Member

  7. HiFidelity

    HiFidelity Guest

    I too vote no teeth, less noise and superior surface skimming. Here are some photos I googled for you;
    External Bean Animal
    [​IMG]

    External Coast to Coast
    [​IMG]

    Another
    [​IMG]

    Another
    [​IMG]

    These photos have different types of external overflows, but all are the type you mentioned you want to build (4 sided box siliconed to the back of your tank) I would recommend you also consider the reef savvy design which is the same in theory except you'd have a 5 sided box bolted to the back of the tank via bulkheads.

    Frankly I would recommend you use acrylic and make 2 full boxes that you bolt onto the tank with bulkheads, these can't fail unless bulkheads fail so you never have to worry about leaks, some feel that acrylic is easier to work with than glass and others feel the opposite is true. Comes down to what you are most comfortable working with since you are having to build it haha.

    If you haven't yet, take a look at the reef savvy ghost overflow, it's probably the best example of what I am describing;
    [​IMG]

    Just my .02 :)
     
    Last edited: Jan 23, 2015
    Coral reefer likes this.
  8. tygunn

    tygunn Webmaster

    Out of curiosity, how are you going to cut the glass to make the overflow slot?
     
  9. Jeremy

    Jeremy Guest

    [​IMG]

    This is pretty much exactly what I'm looking to do! Thanks for looking those up for me, I really appreciate it. I'm still considering the 2 acrylic box option as well just not sure which way I will end up going.

    I'm planning on using a 4" Rockwell saw with a diamond blade. I'll then use another diamond attachment on a Milwaukee 35,000 rpm rotary tool to finish cutting the corners and smooth/round all the cut edges.

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    aqua-nut likes this.
  10. tygunn

    tygunn Webmaster

    Hmm, interesting. I wouldn't have thought of that. I'm looking forward to seeing how it works out for you.

    External overflows are great; doesn't waste space in the tank and nice and shallow for easy maintenance.

    Are you going to glue some colored acrylic on the inside to hide it more or just leave it see-through?
     
    aqua-nut and Coral reefer like this.
  11. aqua-nut

    aqua-nut Supporting Member

    Last edited: Jan 27, 2015
    HiFidelity likes this.
  12. HiFidelity

    HiFidelity Guest

    Damn it, you guys are making me want to cut my new tank :confused:

    I bought a cube recently w/ starphire front pane but it has a horrendous corner overflow that I was going to live with....

    If I do that tank then I'll end up cutting my 50 as well because I'm weird that way :(

    Seeing that dremel in that link did it... had no idea you can dremel any shape into glass that way. Better yet with a rimless the cut can be made even if it's full of livestock.
     
  13. Jeremy

    Jeremy Guest

    Go for it!I'm hoping to do mine either this weekend or next week just having a small issue right now.

    Well I've been looking around and am having a hell of a time finding a diamond blade for my saw. I found tons of 4" blades but none have the right size arbor hole. For some reason they used a 3/8" arbor size which makes it difficult sometimes to find speciality blades. I had one once but the manufacturer quite making 4" blades all together.

    So know I'm trying to decide if I want to use a 7" blade in a skil saw or if I just want to use the rotary tool with the diamond bit in it for the whole thing. It would work but would take considerably longer.

    Decisions decisions!!!

    I've also got to do a quick water test/inspection on the tank because it's been sitting in my garage for the last year or so. Hoping I don't have to add a reseal job to my to do list also!

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  14. gaberosenfield

    gaberosenfield Juvenile Chromis over an Acro in the Red Sea

    I cut a 1" x 11" slit in the side of my 75 gallon glass tank. I planned on using a diamond dremmel bit, but that was taking so long I came up with another technique. Draw out the slit you want on the glass. Then use a diamond hole saw the same diameter as the width of the slit you want cut and cut overlapping holes until it makes a "toothy" slit in the tank. Then you just use a diamond bit and eventually sandpaper to smooth out the "teeth". This technique also has the benefit of making perfectly rounded edges to your cut.
     
  15. rygh

    rygh Supporting Member

    Sounds like a lot of careful work. Glad you did not break the glass!
     
  16. gaberosenfield

    gaberosenfield Juvenile Chromis over an Acro in the Red Sea

    I did on the first try, but not while cutting the slit. I broke the back pane when I was drilling a normal hole to plumb my refugium to the DT :-(
     

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