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tank project overflow


treesprite

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I want to get a 75 to play with, to make an external c2c overflow to preserve tank space. I would be taking off the back pane and having it cut down a couple inches, then have some glass cut to build on the overflow. I still have the front pane from the 75 tank that I broke, so it would just need to be cut. I would like to drill the overflow holes on the bottom of the overflow.

 

What I would like to figure out, is what the best way would be to build in the overflow. It was easy to build on the external on the 65g I had, but that was not a c2c.

 

Of course I need to find a cheap 75g first.

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I've built internal C2C overflows in my last 2 tanks, but both times I found the overflows to be not ideal. The 75g I broke, broke (the back corner) when I was trying to pull off the upper rim to take out the overflow to re-do it. That overflow stuck too far out in the tank for as deep as it was. The 75g I have now, I made the overflow stick out only 1" but had to make it about 6" high because the holes in the tank were drilled too low (someone else drilled). It doesn't look all bad like the old 75g's, but I need to have some silence here and can't fit pvc pieces in 1" width, plus fish go in the overflow and it's nearly impossible to get them out.

 

I was actually saving the old glass in case I broke another tank....

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I'm afraid of there needing to be support. I guess it depends on how much/how heavy the water is that will be going through the OF.

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You could make an acrylic overflow box that straddles the cutout in the tank back wall. It would cutting off a the long strip of glass from the back wall, and replacing it with a slightly taller piece of acrylic siliconed to the inside of the back wall.

 

Or you could fix the drain pipes to something stable like the stand so the pipes help take the weight off the overflow box.

 

If you don't want to work with acrylic, you could attach some triangular gussets between the outside back wall of the tank and the bottom of the overflow box.

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I'm afraid of there needing to be support. I guess it depends on how much/how heavy the water is that will be going through the OF.

If the plumbing is supported, the back wall of the overflow will add a tremendous amount of rigidity to the bottom pane of the overflow. Also, the bottom of the overflow will act as a Eurobrace for the back wall of the tank. The concern that I would have is whether or not the adhesion between the aquarium side panes and the side panes of the external overflow (butt-jointed) will be strong enough not to pull away. If you support the plumbing that's hanging from it, I don't think you'll have any problem. If you're concerned about that, you might be able to add some blocking under the overflow that act like little shelf supports.

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I like the ideas of supporting the pipe. I think with that and cutting the two ends so they angle and extend below the external box for added support you have a solid box. Add in a couple of the gussets as Jon mentioned and you will be fine. I'm not worried about the water weight but more of the drain pipes applying stress on the external box.

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I wish I still had pictures from the 65g - can't find them anywhere (Vadim took that tank... wonder if he still has it?).

 

The overflow I had put on the 65 was actually set into the tank creating a shelf, but I can't for the life of me remember how I did it. It had 3x 1" holes drilled into the bottom glass (I used glass from a 10g tank which I cut down, had about a 1g volume). I also used a piece of glass as a center brace, and used upper trim from the now taken apart 10g around the top of the overflow.

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(edited)

I just remembered why I can't do the overflow like that one. That tank was cut down like 7", so the bottom of the overflow was bigger than the top and was inserted into the tank forming a shelf and providing support, then a piece of glass put back over the space but a couple inches shorter... gets complicated. I had a seam all the way across the back of the tank from putting it back together... blah blah blah....

 

In this case, the bottom of the box will be lower than the edge of the tank. I guess there's no way to do that.

 

Would a narrow shelf at the top edge of the overflow make for better surface skimming, since it would thin out the water more? Also, would it help keep fish from going over even without some kind of guard?

 

I can't visualize without some pieces of glass to play with.

Edited by treesprite
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(edited)

I found pics of the overflow on the 65g.

 

eo2-1.jpgeo1.jpg

 

The overflow wasn't C2C on here, but seeing this is helpful. If this had been a C2C, I would not have had to put that big ugly patch glass on the tank (was overkill... had a panel on the outside and the inside, epoxied and siliconed... no way that was coming apart).

 

So really, I could do it like I did with the 65g, but have a shelf the entire length of the tank on which to grow things, instead of a big ugly patch. *The shelf is the bottom of the overflow box which extends into the tank. I don't think I would want it that wide, but would like just 1 or 2" be enough to greatly improve support?

 

(note: that overflow box was not a part of a thin-glassed 2.5g tank as someone thought back then - it was glass from a 10g tank that I cut myself, with the front being the glass of the 65g, and the trim was the trim from the demolished 10g)

Edited by treesprite
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(edited)

I think I still have the upper rim from my old 75g (the one I broke). I am going to have to cut the back part of the trim off the tank to put the overflow in anyway, so I can use the old trim to enlarge the entire thing to go all the way around, holding together the tank AND the back wall of the overflow (which would have to be the height of the tank glass, not the height of the front wall of the overflow).

 

I will have to cut the center brace of the tank though. I'm not sure what to do about that. What about getting a piece of glass cut to make a brace going from the front of the tank to the back wall of the overflow?

 

That would all be plenty of support for the overflow to make me feel at ease, not worried about plumbing pulling it down. The inset box bottom (shelf), the trim bracing, and the center brace.

 

What do you think?

Edited by treesprite
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I found the trim. It's the same as the trim on my currently operating 75g - I'm assuming most 75gs will fit this same trim. I'd just do this with the tank I have now, except that I prefer not having my fish and rocks and corals divided up into smaller tanks for a long time. If I have another tank, I only have to put the fish in other containers long enough to get the newer tank set up on the stand and filled.

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(edited)

This is view from above tank looking down:

 

tankoverflowproject.jpg

Edited by treesprite
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Won't the bottom of the overflow box be slightly below the front wall of the box (the back lip of the aquarium)? You'll get better surface skimming if it is. Also, it seems that you really can't "extend" the bottom of the overflow box into the aquarium for the frag shelf if this wall is higher than the bottom of the overflow.

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The shelf is the bottom of the overflow box which extends into the tank. I don't think I would want it that wide, but would like just 1 or 2" be enough to greatly improve support?

 

Making the overflow shelf extend farther into the tank does not provide more support. You'll have the same support whether it extends 6 inches into the tank, 1/16 of an inch, or it's flush.

 

Also, if you make the shelf larger it will be more to keep clean. If you don't keep it clean, it may cast shadows on your reef.

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(edited)

Won't the bottom of the overflow box be slightly below the front wall of the box (the back lip of the aquarium)? You'll get better surface skimming if it is. Also, it seems that you really can't "extend" the bottom of the overflow box into the aquarium for the frag shelf if this wall is higher than the bottom of the overflow.

 

Did you see how it is in the pic from the old 65g? The shelf is created by the bottom of the overflow. How deep the overflow box is, is dictated by how many inches I have cut off the height of the back pane of the tank. The strip of glass that was cut off is to be make narrower then sealed back onto the tank atop of the shelf. The top of the overflow will be the top of that piece of glass, which will be about the height of the lower edge of the tank's trim.

 

 

Making the overflow shelf extend farther into the tank does not provide more support. You'll have the same support whether it extends 6 inches into the tank, 1/16 of an inch, or it's flush.

 

It will be siliconed all the was across, from below and above it, inside and outside of the tank, and siliconed to the strip of glass that will be the front wall of the overflow. It might also help to slightly extend the side walls of the overflow, because then I can seal the outsides of the overflow sides to the insides of the tank end walls.

 

If I simply cut off only a couple inches and attach a box to the back of the tank on the outside of the tank back, there will not be enough support. If I do it this way, it will be inserted into and sealed to the tank itself.

 

Also, if you make the shelf larger it will be more to keep clean. If you don't keep it clean, it may cast shadows on your reef.

 

I think I would only extend it an inch or two, not 4" like the pic from the 65g. That is far enough to be able to seal the overflow securely into the tank. It would be wide enough to put a small frag plug, not wide enough to get in the way of anything. Overflows inside of the tank take away tank space and cause shadows a heck of a lot more than that. Also, it would be a lot better than having an ugly hang-in frag rack in the tank, which causes shadow and has to hang on the front or side of the tank disrupting the viewing areas of the tank.

 

I got a couple 10g tanks from Petco, thinking I might use those to test this out, but I'm hesitating because I don't know what I would do with a 10g tank with an external C2C OF.

Edited by treesprite
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Did you see how it is in the pic from the old 65g? The shelf is created by the bottom of the overflow. How deep the overflow box is, is dictated by how many inches I have cut off the height of the back pane of the tank. The strip of glass that was cut off is to be make narrower then sealed back onto the tank atop of the shelf. The top of the overflow will be the top of that piece of glass, which will be about the height of the lower edge of the tank's trim.

I see. So the bottom shelf sticks out like a tongue back into the tank and you silicone back in a narrowed strip to create a dam over that.

 

Personally, I'm not to crazy about the extra siliconed joints just to extend the shelf this way. Have you thought about just siliconing a separate shelf inside the tank, or maybe putting something together that discretely hangs over the side of the overflow and into the tank? At least then, you have the flexibility of removing, reshaping or even repositioning it later. If you make it an integral part of the overflow, you don't have that flexibility.

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The shelf thing is only a matter of me having a way to install the overflow - I can really do without it. I'm just afraid that simply attaching the overflow to the outside of the tank back will not give me enough support. If I can get enough support just siliconing to the back, I only have to have an inch or two cut off the top of the back tank glass. But someone raised the concern about the support and it seems a reasonable concern to me.

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The shelf on the inside won't do anything to add strength, unfortunately. Add some blocking, if desired, outside the tank and under the shelf to add support against sagging. Jon mentioned "gussets." That's what I think he, Coral Hind, and I are thinking would add the extra support, not necessarily needed, but desired.

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Steve Outlaw builds tanks then sells them after a few months only to build again....

Forrest makes DIY frankentanks then breaks them after a few months only to build again...

I hear wedding bells. :tongue:

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(edited)

Steve Outlaw builds tanks then sells them after a few months only to build again....

Forrest makes DIY frankentanks then breaks them after a few months only to build again...

I hear wedding bells. :tongue:

 

Ah, but I have not broken the current one! I'm striving for a better overflow.

 

If all I need to do is attach the box to the back of the tank (with supports), all I have to do is grind teeth across the top (would use a dremmel), or better yet, slots so I won't have to even remove the tank trim (start with a tiny hole for each one). I actually recently started to grind teeth into the top of my current overflow, but only did 5 or 6 little ones before I decided I should just make a better overflow. Then I could make the overflow either all the way end to end, or leave a few inches on the ends, or put gaps or whatever I want to have more control. It would be rather time consuming, but less trouble/less worry than taking apart the tank, going to the glass shop for cutting, worrying about the cutters, and re-sealing the tank. I'm getting good with diamond coated grinding discs, and they are cheap at HF Tools. Glass is fascinating.

Edited by treesprite
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I was thinking about the tank glass as far as cutting... I'd still have to get the box glass cut, but if that goes wrong it's not a big deal.

 

Some other questions I have...

- what thickness of glass? I'm guessing now that the old glass from the broken 75 would be too heavy.

- how would I go about painting the back glass? I can't do it before applying silicone, but I don't want to see the siliconing from the front of the tank.

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(edited)

Slots ground into glass from a 75g tank.... these are sloppy, but just wanted to demonstrate that it can be done.

 

slots.jpg

hmmm... just noticed my camera date is 2 days off

Edited by treesprite
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