Overflow help...

[Heelfiend]

So I bought a 120g tank that has already been drilled. The thing is it is drilled in the upper back corners of the tank, not through the bottom. All of the drain guides I have seen have the directions for DIY plumbing with the holes through the bottom. Are both holes supposed to be for two drain lines or one for drain and one for return?

Any help and/or links would be much appreciated. And yes I am a noob, as evidenced by my question. :spin1:

 

[thegrun]

I suspect the two holes are for the return lines using an over the top overflow box for drainage. If possible (if the glass in your tank is not tempered) I would drill new drain lines rather than use an over the top overflow.

 

[Heelfiend]

I suspect the two holes are for the return lines using an over the top overflow box for drainage. If possible (if the glass in your tank is not tempered) I would drill new drain lines rather than use an over the top overflow.

In the bottom? I definitely do not feel comfortable drilling, what's a standard charge for that from a glass company?

 

[Heelfiend]

Can one be used for the drain and one for the return? I'm still not 100% on the physics of this stuff even after reading a bunch of material.

 

[tatuaje08]

Check out the overflow kits at glass-holes.com.

 

[Heelfiend]

Check out the overflow kits at glass-holes.com.

I have been looking at those, but my question is more physics/designed based than looking for a specific product.

 

[tatuaje08]

I have been looking at those, but my question is more physics/designed based than looking for a specific product.

Right. They offer overflows that utilize a hole driled in the back, not the bottom. So, holes placement will depend on what type of overflow you want. A standpipe overflow will require a hole in the bottom, glass-holes style requires a hole in the back.

 

[Heelfiend]

Right. They offer overflows that utilize a hole driled in the back, not the bottom. So, holes placement will depend on what type of overflow you want. A standpipe overflow will require a hole in the bottom, glass-holes style requires a hole in the back.

Can I utilize one of the holes for a drain and one for the return? I am confused as to if that would provide enough GPH and if it matters that the return and drain would be on the same "level" in the back of the tank.

 

[tatuaje08]

You could. First you'd have to figure out what gph turnover you want. Then you would have to make sure the holes are the right size. Another option would be to use the current holes as two returns, drill a hole in the bottom and install a durso style overfow. Of course you would have to make sure the bottom is not tempered glass, or else it will crack when you drill it.

 

[anbosu]

If you post a pic you will get better advice, but I would use both for drains and bring your returns over the top

 

[oscarinw]

Yes you can use one for return and one for overflow.
I would personally use both for drainage with two overflow box kits on the outside and run dual return lines in the middle of the tank over the edge. That way you double your drainage capacity specially if the holes are 3/4" or less. If they are 1", then you should be fine using one as drain and one as return. Plan your return pump really well.
Good luck with things.

 

[Heelfiend]

Holes are huge which makes me believe one was used for drain and one for return. I want to say the holes are around 2 inches in diameter.

 

[animalkingdom]

they sound like dual overflow holes to me...
I would do a dual overflow through the holes setup with an over the top return if I were you. Not many returns are 2''

 

[tatuaje08]

they sound like dual overflow holes to me...
I would do a dual overflow through the holes setup with an over the top return if I were you. Not many returns are 2''

+1.

I'm not a fan of dual overflows, but it sounds like that's what you have.

 

[Heelfiend]

Okay so I measured the openings and they are 1.75" in diameter. Still too big to use as a return I guess? Honestly I'd rather have everything internal and quiet to boot.

 

[tatuaje08]

You could use an adapter to go from a smaller hose to the larger bulk head

 

[fishgate]

What is on the tank side of the holes?

 

[Heelfiend]

What is on the tank side of the holes?

I'm not sure what you mean by that. There's nothing, it's an empty tank with two holes drilled in the back.

 

[shaggss]

You said in the concerns, so have you got two holes in each corner (total four holes), one hole in each corner (total two holes) or two holes in one corner?

I would seriously think about an internal weir and do a beananimal overflow. This is the best overflow possible. Quiet, fail safe and no bubbles.

Read THIS thread for more ideas.

 

[Heelfiend]

You said in the concerns, so have you got two holes in each corner (total four holes), one hole in each corner (total two holes) or two holes in one corner?

I would seriously think about an internal weir and do a beananimal overflow. This is the best overflow possible. Quiet, fail safe and no bubbles.

Read THIS thread for more ideas.

One hole in each corner, sorry for the confusion. Thanks for the link.