Internal Coast to Coast Overflow Design

[SnowyFox]

This is the design for an internal coast to coast overflow I'm leaning towards installing in an old tank I'm working on restoring (just got it used from my LFS). Was hoping to get some sanity checking on the design before I pull the trigger on fabrication. The tank it's going in used to have corner overflows and an acrylic panel siliconed to the inside of the back glass. The back glass has a lot of etching on it, along with where the corner overflows were originally attached to the side glass panels, which I've been unable to remove.

The goals with this design was to hide all of the etching on the back and sides of the tank, and to convert the 2 original independent corner overflows into a single coast to coast style overflow that spans the back of the tank. The plan would be to use the (2) 1" bulkheads as the primary and secondary drains, and the (2) 3/4" bulkheads for the emergency drains in a bean animal overflow setup. The tank is 160 gallons, so I'm aiming to have 1600 - 2000 GPH of flow going through it.

Concerns:
- Is a 3/4" gap between the back glass and the overflow going to cause headaches down the road with cleaning issues?
- Can I achieve a 1600+ GPH flow rate through this setup?
- Is 1/4" acrylic thick enough for this? or should I go with 3/8" instead?
- Should this be installed at the same time I reseal the tank? or installed after the resealing has partially / fully cured?

If this is a bad design, then the alternative options are:
- Install new corner overflows and a back panel like the tank originally had
- Drill back of tank for an external overflow rated for 2000 GPH, and cover back glass inside with an acrylic panel. Side glass would likely still show etching

 

[Dburr1014]

This is the design for an internal coast to coast overflow I'm leaning towards installing in an old tank I'm working on restoring (just got it used from my LFS). Was hoping to get some sanity checking on the design before I pull the trigger on fabrication. The tank it's going in used to have corner overflows and an acrylic panel siliconed to the inside of the back glass. The back glass has a lot of etching on it, along with where the corner overflows were originally attached to the side glass panels, which I've been unable to remove.

The goals with this design was to hide all of the etching on the back and sides of the tank, and to convert the 2 original independent corner overflows into a single coast to coast style overflow that spans the back of the tank. The plan would be to use the (2) 1" bulkheads as the primary and secondary drains, and the (2) 3/4" bulkheads for the emergency drains in a bean animal overflow setup. The tank is 160 gallons, so I'm aiming to have 1600 - 2000 GPH of flow going through it.

Concerns:
- Is a 3/4" gap between the back glass and the overflow going to cause headaches down the road with cleaning issues?
- Can I achieve a 1600+ GPH flow rate through this setup?
- Is 1/4" acrylic thick enough for this? or should I go with 3/8" instead?
- Should this be installed at the same time I reseal the tank? or installed after the resealing has partially / fully cured?

If this is a bad design, then the alternative options are:
- Install new corner overflows and a back panel like the tank originally had
- Drill back of tank for an external overflow rated for 2000 GPH, and cover back glass inside with an acrylic panel. Side glass would likely still show etching

About the 3/4 thickness from the back of the tank to the Overflow, I see that as a detritis trap. You may want to go a little thicker maybe 1" or 1.25 so you can get a hose back there to squirt around and get that stuff out.

 

[TX_REEF]

agreed, that small gap will be a headache down the road. Why do you want coast to coast like this, out of curiosity? It seems two corner overflows would do just fine and be much simpler

 

[SnowyFox]

agreed, that small gap will be a headache down the road. Why do you want coast to coast like this, out of curiosity? It seems two corner overflows would do just fine and be much simpler

Mainly the ease of tuning a single overflow vs two separate ones. Also seemed like those who had coast to coast style overflows seemed to really love them ‍

The last tank I had was a 125 with 2 HOB overflows, and they were a real pain to tune, and quite noisy. That tank blew a seam, and needs to be fully rebuilt to ever be usable again, which is why I picked up this used tank. I was really wanting to go with an external overflow on this one, but I didn't realize how bad the back glass was damaged from etching when I bought it. A coast to coast overflow just seemed like something I could do, and could be an upgrade from going with just corners.

 

[TX_REEF]

Mainly the ease of tuning a single overflow vs two separate ones. Also seemed like those who had coast to coast style overflows seemed to really love them ‍

The last tank I had was a 125 with 2 HOB overflows, and they were a real pain to tune, and quite noisy. That tank blew a seam, and needs to be fully rebuilt to ever be usable again, which is why I picked up this used tank. I was really wanting to go with an external overflow on this one, but I didn't realize how bad the back glass was damaged from etching when I bought it. A coast to coast overflow just seemed like something I could do, and could be an upgrade from going with just corners.

it's your adventure, don't let my laziness stop you

 

[YOYOYOReefer]

my tanks have coast to coast and I do love it Mine is only 4 inches wide and if I were doing it over I would have made it 6 inches wide so I could keep reactors etc in there
but if you don’t need access your 3/4 should be fine. Imo you do need enough room in there for bulkheads

 

[Daveobrien]

About the 3/4 thickness from the back of the tank to the Overflow, I see that as a detritis trap. You may want to go a little thicker maybe 1" or 1.25 so you can get a hose back there to squirt around and get that stuff out.

This isn't just a detritus trap, it's ideal Aptasia growing conditions. Get even one, and you'll never get it clean again - you'll have Aptasia in there Forever.

 

[SnowyFox]

This isn't just a detritus trap, it's ideal Aptasia growing conditions. Get even one, and you'll never get it clean again - you'll have Aptasia in there Forever.

What makes it ideal for that? I'm not familiar yet with Aptasia. I was thinking about painting the glass behind the overflow black to try to eliminate all light back there, along with making some lids / covers that would sit between a 1/4" to 1/2" above the overflow to also block light and prevent most fish / creatures from exploring inside of it

 

[Dburr1014]

Could always do one corner overflow and make it a Herbie.
Window tint the back glass

 

[mfinn]

I had a tank that had a messed up back wall and it had double bulkheads in each corner. I got a sheet of blue 3/8" acrylic and had a local tank builder make 2 overflow boxes for each side and cut a piece of acrylic to fit in-between the two overflow boxes and go from tank bottom to the top. Siliconed everything in. Had the tank up and running about 10 years before passing it on to a friend.

 

[SnowyFox]

I had a tank that had a messed up back wall and it had double bulkheads in each corner. I got a sheet of blue 3/8" acrylic and had a local tank builder make 2 overflow boxes for each side and cut a piece of acrylic to fit in-between the two overflow boxes and go from tank bottom to the top. Siliconed everything in. Had the tank up and running about 10 years before passing it on to a friend.

That sounds like one of the backup plans I'm considering, just in black instead of blue.

 

[Daveobrien]

What makes it ideal for that? I'm not familiar yet with Aptasia. I was thinking about painting the glass behind the overflow black to try to eliminate all light back there, along with making some lids / covers that would sit between a 1/4" to 1/2" above the overflow to also block light and prevent most fish / creatures from exploring inside of it

Stuff always grows in overflows. If you can't reach into the gap to scrape the sides and the bottom, you'll never get it out. Aptasia are the classic beast that lives in overflows. Anytime food isn't eaten and goes over the overflow, an Aptasia will catch eat it... and reproduce and make more aptasia.

 

[SnowyFox]

Stuff always grows in overflows. If you can't reach into the gap to scrape the sides and the bottom, you'll never get it out. Aptasia are the classic beast that lives in overflows. Anytime food isn't eaten and goes over the overflow, an Aptasia will catch eat it... and reproduce and make more aptasia.

If I made that gap large enough for a long handled algae scraper to fit in (1" to 1.5"), do you think that would be sufficient for cleaning down the road?

 

[mfinn]

That sounds like one of the backup plans I'm considering, just in black instead of blue.

Yeah everybody was in a blue phase, just before black got popular.

 

[Daveobrien]

If I made that gap large enough for a long handled algae scraper to fit in (1" to 1.5"), do you think that would be sufficient for cleaning down the road?

significantly better. Yes.

 

[exnisstech]

If you can't reach into the gap to scrape the sides and the bottom, you'll never get it out. Aptasia are the classic beast that lives in overflows. Anytime food isn't eaten and goes over the overflow, an Aptasia will catch eat it... and reproduce and make more aptasia.

Your supposed to scrape and clean your overflows? I definately missed that memo. Overflow is temporary housing untill they make their way to their sump.

 

[RocketEngineer]

Personally, I would build a bridge vs a wall. I can picture two vertical boxes supporting a full width horizontal box. If working in Acrylic, the center of the bridge can be narrowed but I wouldn’t go below about 3” wide so I could reach inside. JMO