Drilling a 18" Cube and a have a few questions.

[Shard]

I haven't worked will drilling a tank, or installing an overflow in years, so I have obviously forgotten some things... I am putting a drain/return in an 18" Mr Aqua Cube I just purchased, and I have a few questions. I am wanting a center of the back-wall, full height overflow.

 

1.) I know the standard return line is 3/4", but what size drain bulkhead should I put in?

 

2.) Should the holes be a certain distance apart? or certain distance from the back wall? Or can I place them as close together (considering the size of the actual bulkheads) as will fit to be most efficient with space?

 

I am going along the back wall in the center, but I don't want to put it too close to the edge and make the glass easy to crack around the holes, but I do want to keep the overflow as small as possible to maximize my display area. Any general rules of thumb for this?

 

3.) Should I consider just using the full height overflow for the drain only, and putting the return line into the tank directly through the bottom of the tank.. sort of like a closed loop, but have a PVC pole coming up through the sandbed? Its a rimless tank and I want to keep the look as clean as possible, without lines running all over the place behind it.

 

4.) Should I consider one of the small skimmer boxes/overflows? The kind that mount near the top of the tank and you drill through the back glass near the top for an external overflow? Would maximize display space.

 

Thanks!

[jestep]

How much flow are you planning on running from your sump?

 

1. At least a single 1" overflow or at least 1 size larger than the return.

 

2. At least 1" from any edge, more if possible. You can get a threaded bulkhead and use locline to modify where the flow is directed. Locline MPT fittings are available in both 1/2 and 3/4. Personally, I would think a 1/2" return would be plenty sufficient for this size tank and is a much smaller bulkhead than 3/4.

 

3/4. One thing you could do is paint, or use film, on the back wall and then drill a return near the top of the tank. You wouldn't need to have PVC coming up through the sand in this case. Same thing goes for the overflow itself. I would prefer a horizontal mounted overflow box to a full height one on a tank this size. The space at the bottom is premium IMO.

[Shard]

How much flow are you planning on running from your sump?

 

Well, if the usual turnover rate is 10x, somewhere around 250gph.

 

2. At least 1" from any edge, more if possible. You can get a threaded bulkhead and use locline to modify where the flow is directed. Locline MPT fittings are available in both 1/2 and 3/4. Personally, I would think a 1/2" return would be plenty sufficient for this size tank and is a much smaller bulkhead than 3/4.

 

Sounds good... 1/2 return with 1" drain.

 

3/4. One thing you could do is paint, or use film, on the back wall and then drill a return near the top of the tank. You wouldn't need to have PVC coming up through the sand in this case. Same thing goes for the overflow itself. I would prefer a horizontal mounted overflow box to a full height one on a tank this size. The space at the bottom is premium IMO.

 

I want the back wall clear, but I think I will go with a short drilled return box at the top, you are right space is premium.

 

I just can't decide if I want the return drilled through the back wall, or coming up from the floor of the tank. Not sure what I would like better... a 18" tall black PVC 1/2 pipe in my tank, or a line clearly visible running to a bulkhead near the top of the tank.