Help with plumbing a used tank

[SauceK]

Hi all! I bought a 180g acrylic tank with dual overflows secondhand. And I am just a little lost on how to do the plumbing. There are multiple holes on the tank, just wondering if they are output/input in terms of flow. Here are pics of the tank, if you guys can redirect me to any educational plumbing videos that would be great as well. Thanks in advance!

 

[Albertan22]

The hole in the back of the tank is for a return line to bring water in from your sump and return pump. The one inside the overflow box will be a drain. I would guess that the one in the top bracing is to run wires through but it could have been for a return line at some point. Is there another hole in the bottom located outside the overflow box or is that a rubber washer sitting there?

You need to get some appropriately sized bulkheads to put into the holes then can attach solid or soft plumbing from there depending on your preferences.

 

[SauceK]

removed comment

 

[SauceK]

The hole in the back of the tank is for a return line to bring water in from your sump and return pump. The one inside the overflow box will be a drain. I would guess that the one in the top bracing is to run wires through but it could have been for a return line at some point. Is there another hole in the bottom located outside the overflow box or is that a rubber washer sitting there?

You need to get some appropriately sized bulkheads to put into the holes then can attach solid or soft plumbing from there depending on your preferences.

It is actually another hole! which is why I was a bit thrown off, i thought it matched with the hole in the back wall.

 

[Albertan22]

It is actually another hole! which is why I was a bit thrown off, i thought it matched with the hole in the back wall.

That is strange, typically there would be two holes in the overflow, one for the drain and a smaller one for the return. I don’t know why there would be a hole outside the overflow, maybe they had it plumbed for a closed loop?

 

[SauceK]

Bump, does anyone know what this hole is used for? My only speculation would be another drain pipe/emergency overflow?

 

[fcmatt]

I would so cover that inside bottom hole up so well it would never leak even if the devil was poking at it.

 

[SauceK]

So I just asked the old owner of the tank what the hole was used for. Apparently, it was used for a return line! I've been doing research and I'm a bit hesitant to connect the return to the sump in case of pump failure and draining my whole tank. Seems to me that no one trusts check valves to work.

I'm open to any suggestions for how to plumb a bottom drilled return line!

One thing I was thinking about doing is maybe making a closed loop system and drilling another hole in the back as the inlet and pumping the water back under as a back draft type of wave.

 

[Albertan22]

You could put a bulkhead and glue in a pipe that came up to close to the surface, then add a 90 and go to loc line. It would be pretty ugly though, you'd have to hide it with rock OR install a bigger overflow box that hid both that return hole and the drain. Having a return right in the bottom, without a pipe to the top, is basically a bathtub drain for your entire tank to drain to the sump if the power goes out or you need to shut down a pump for maintenance. If I were to use it without adding some kind of lift pipe to the top of the tank, I would do some kind of closed loop and make sure to install ball valves so I could close that off for pump maintenance.

 

[SauceK]

Yea, I think I might just make a closed loop system. Both of the return holes (left and right) are 1 1/4". Do you think if I just drilled one 2" hole in the back it would be a big enough diameter flow wise? I'll try to post a drawing of plumbing schematic tomorrow.

 

[SauceK]

Here's a schematic of the closed loop system. I haven't drilled the red hole in the back, but I was thinking of making it a 2" hole. With a ~1600 gph return pump.


Regarding the sump system, both of the return holes in the back are 2", I'm planning to use a Current eFlux DC Pump (3160 GPH). I'm hoping that can handle enough head pressure. Or maybe I should reduce the diameter to 1 1/2" ?

Thanks for all your help and input, Albertan22!

 

[Albertan22]

Not having drilled a tank myself, I’d say to make sure you have the bulkhead you want first and drill the appropriate hole for the bulkhead. You only get 1 shot at drilling glass. In terms of flow, there are charts such as this one that give you an idea of how to size it to match a pump:

https://hy-techroofdrains.com/water-flow-through-a-pipe/

That should help both the drain and the return. You will have to consider what you are intending for the return ends. If you are leaving them with just a bulkhead, they will shoot a jet straight upwards and you may not want a huge pump, I assume you rig up something directional though.