How to fix weird 2nd hand tank design

[Latte]

Hey guys, just picked up a secondhand tank a week ago and it's been running since then. This tank will only be run as a FOWLR, with no plans to add corals.

Now, I've noticed a pretty big flaw in the design of the tank. At the moment, there's a AIO style back section along the whole back of the tank (it's mostly empty). The water only enters the back of the tank through a small circular hole in the wall between the DT and back, this is highlighted yellow in the diagram below. The water then enters the left side of the back, there's a bit of rock but otherwise the space is empty. Then the water flows over the baffle into the weir, and down the overflow into the sump.

My question is, it seems like there's no real ability for stuff like uneaten food to be sucked out of the water column and into the sump for filtration, especially as the back of the tank is full of rock at the moment. Is there any way I can fix this? Thanks all!

 

[fishguy242]

hi, where are returns ?
is this acrylic ?

 

[Latte]

hi, where are returns ?
is this acrylic ?

Return is at the top, just to the right of the yellow circle. It's glass not acrylic

 

[fishguy242]

was hoping it was acrylic.
so basically a lower intake ,and a weir.
guess not so bad ,will filter water at top and near bottom.
just need a high flow in tank ,especially toward that lower corner.

 

[Latte]

was hoping it was acrylic.
so basically a lower intake ,and a weir.
guess not so bad ,will filter water at top and near bottom.
just need a high flow in tank ,especially toward that lower corner.

I don't really want to put a powerhead in the back though, and feel like everything is just going to settle out into the rocks in the back of the tank otherwise no matter how much flow is in the actual tank.

I'm not even really sure how to get the detritus through the hole as most of the time it seems you get the gunk out of the tank by using power heads to get it up off the bottom. It's a lot harder to get the detritus into the water column but keep it at the perfect height than it is to get it just to the top so it flows into the overflow. Hmm...

 

[fishguy242]

is it a bulkhead,or just a hole?
if bulk ,you can put a 90 on it and raise to desired height ?

 

[Latte]

is it a bulkhead,or just a hole?
if bulk ,you can put a 90 on it and raise to desired height ?

It's literally just a hole haha, pretty unique design...

Guessing moving the rock out of the way is a good place to start, might be a bit hard to get my arm back in there though.

 

[fishguy242]

check size, most likely will fit bulkhead

 

[Eagle_Steve]

It's literally just a hole haha, pretty unique design...

Guessing moving the rock out of the way is a good place to start, might be a bit hard to get my arm back in there though.

Can you post a full picture of the tank and top portion showing the overflow?

I have seen a tank setup like this before, but it was a while ago. The tank was setup to have a bulkhead in the lower hole and a small pump in the chamber to create a sort of closed loop. Water would be pumped out, but the actual overflow towards the top would be for what it typically is.

 

[Latte]

Here are some pictures. Thanks so much for your help so far guys, I'm not really sure what you mean by the bulkheads and closed loop sorry.

Here is the full tank: hole is in bottom left, overflow on right, return top left.

Here is the top of the tank. Overflow in back left, the weird back chamber is front left. Return and DT on the right.

 

[fishguy242]

yep, definitely have not seen one of these before...

 

[Latte]

yep, definitely have not seen one of these before...

:/ What do I do... This seems concerning

 

[fishguy242]

get exact measurement on hole ,lets start there

 

[Rmckoy]

I don't really want to put a powerhead in the back though, and feel like everything is just going to settle out into the rocks in the back of the tank otherwise no matter how much flow is in the actual tank.

I'm not even really sure how to get the detritus through the hole as most of the time it seems you get the gunk out of the tank by using power heads to get it up off the bottom. It's a lot harder to get the detritus into the water column but keep it at the perfect height than it is to get it just to the top so it flows into the overflow. Hmm...

Is the hole in the bottom at the back meant to be a return ?

I had a 90 gal tank drilled in the bottom for the return .
it had a check valve to prevent flooding .
The overflow was drilled on the left side with bulkheads

 

[Lbrdsoxfan]

Can you post a full picture of the tank and top portion showing the overflow?

I have seen a tank setup like this before, but it was a while ago. The tank was setup to have a bulkhead in the lower hole and a small pump in the chamber to create a sort of closed loop. Water would be pumped out, but the actual overflow towards the top would be for what it typically is.

This. I had a small pump that was in the overflow chamber routed to the hole on the bottom. It was a pseudo closed loop design, to move water at the bottom of the tank. The only difference was that it was acrylic and not glass. I used it for a bit but I ended up sealing it with a bulkhead & plug than I glued piece of acrylic over the hole. That was over 10 years ago.

 

[Latte]

get exact measurement on hole ,lets start there

hole is 4cm in diameter

Is the hole in the bottom at the back meant to be a return ?

I had a 90 gal tank drilled in the bottom for the return .
it had a check valve to prevent flooding .
The overflow was drilled on the left side with bulkheads

I don't think so? There's already a return pipe in the back right.

This. I had a small pump that was in the overflow chamber routed to the hole on the bottom. It was a pseudo closed loop design, to move water at the bottom of the tank. The only difference was that it was acrylic and not glass. I used it for a bit but I ended up sealing it with a bulkhead & plug than I glued piece of acrylic over the hole. That was over 10 years ago.

Hmm so what should I actually do? I'm pretty newbie when it comes to plumbing as I've only had an AIO before and just want to figure out the best way to prevent this tank becoming a detritus trap.

 

[fishguy242]

3/4" bulkhead size hole. 1.56"