Plumbing External Overflow.....Is the external box necessary?

[gherewolf]

A long time ago I built my own internal/external low profile type overflow. It has been working great until my external box started to bend outward. (See pic). Bad design on my part for not adding some horizontal bracing.

I need to fix this before it breaks and cases a bigger issue. I’m questioning why I even need the box at all....

I have 2x2 1/2” drains that connect the inside tank overflow to the outside and then three 1 1/2” drains going from the external box to the sump. Flow is not a problem as one of the 1 1/2” pipes can easily handle the entire flow.

Finally the question!

Why could I not just attach 2 elbows straight to the bulkheads that are running to the inside of the tank and get rid of the external box altogether?

 

[GaryE]

A long time ago I built my own internal/external low profile type overflow. It has been working great until my external box started to bend outward. (See pic). Bad design on my part for not adding some horizontal bracing.

I need to fix this before it breaks and cases a bigger issue. I’m questioning why I even need the box at all....

I have 2x2 1/2” drains that connect the inside tank overflow to the outside and then three 1 1/2” drains going from the external box to the sump. Flow is not a problem as one of the 1 1/2” pipes can easily handle the entire flow.

Finally the question!

Why could I not just attach 2 elbows straight to the bulkheads that are running to the inside of the tank and get rid of the external box altogether?

I suppose you could, however, if your sump is already close to full, you may have an issue.

My sump is at about 3/4 full when I shut off the pump. With your idea, I'd easily overflow the sump.

 

[JoshH]

The short answer is you can. However. With the bulkheads being at the same height you won't be able to separate the flow in a one siphon and one secondary drain setup. You'll have two drains at the same height that will more than likely cause all kinds of noise and flow issues....

You could create a larger internal box and place a street elbow on the secondary bulkhead and leave nothing on the primary. This would be a true Bean Animal drain but without the emergency. You would still need some PVC T fittings at the bulkheads and they would more than likely stick out further from the tank than your curren overflow box does but it would work well.

 

[gherewolf]

I suppose you could, however, if your sump is already close to full, you may have an issue.

My sump is at about 3/4 full when I shut off the pump. With your idea, I'd easily overflow the sump.

Ok, makes sense, but I would be keeping the box that is inside the display so when the pumps shut off, only water above that box would drain. I dont

The short answer is you can. However. With the bulkheads being at the same height you won't be able to separate the flow in a one siphon and one secondary drain setup. You'll have two drains at the same height that will more than likely cause all kinds of noise and flow issues....

forgot to mention setup is in garage so noise and room isn’t as much of a concern, however, could I put a gate or ball valve on one of the two 1 1/2” drains to dial in a siphon and then my other drain would be the “emergency”? I just would not have 3 drains like I currently do.

Also, I shut off the current gate valve to see how much flow one drain could handle before hitting the emergency drain height. The one 1 1/2” could handle it all.

 

[JoshH]

however, could I put a gate or ball valve on one of the two 1 1/2” drains to dial in a siphon and then my other drain would be the “emergency”?

The issue here is your two bulkheads are at the exact same height. So even if you put a valve on the one drain, all the flow will be split between the two as theres no height difference. So as you close the one valve all the flows just increasing into the other drain. So the gurgling noise would be tremendously loud and you won't technically have two separate drains.

There is a way around this, you could take your internal box and insert a divider between the secondary drain and the primary and also add a piece to block the lower part of the weird on the secondary side. This would create the height difference needed to differentiate between the two. However that's a TON of work and if not done just right it won't work properly...

And once again, you'd need to add T's on the outside of each drain which would increase the width of space needed behind the tank.

Why the desire to get rid of the rear box?

 

[ca1ore]

I don't follow the sump-will-overflow logic …… as long as you keep the internal skim box, the same amount of water will drain down to the sump regardless of whether you use the external box or not. The bigger issue is the one @JoshH notes. In the original bean animal design there was no external box, rather just three sets of PVC Ts; BUT, the internal box was larger allowing you to install elbows to run a siphon, open channel, etc. Removing the external box here would mean you would either have to run both bulkheads as siphons (unsafe) or both as open channels (noisy). Frankly, I'd just weld on an acrylic brace.

 

[JoshH]

I don't follow the sump-will-overflow logic …… as long as you keep the internal skim box, the same amount of water will drain down to the sump regardless of whether you use the external box or not

I think it was a miss interpretation of the question thinking the OP wanted to remove both the boxes and not just the external box

 

[K7BMG]

In the pictures I don't see the bowing your talking about.
I take that back I see it in the first picture now. But my theory below is still the issue.
I guess your referencing the back plate with the bulk heads into the DT.
As I see the box is at an angle now to the back of the tank, where it might not have been in the beginning.
The real problem is over time the weight of the return lines has caused this.

I would simply raise and support the return lines so they do not hang and pull on the box. add a piece of material behind the return lines so they are straight, and the box straightens out, and strap them in place.

This is a step that seems to always get overlooked when plumbing is done.
Few people strap or support the pipes.

 

[gherewolf]

In the pictures I don't see the bowing your talking about.
I take that back I see it in the first picture now. But my theory below is still the issue.
I guess your referencing the back plate with the bulk heads into the DT.
As I see the box is at an angle now to the back of the tank, where it might not have been in the beginning.
The real problem is over time the weight of the return lines has caused this.

I would simply raise and support the return lines so they do not hang and pull on the box. add a piece of material behind the return lines so they are straight, and the box straightens out, and strap them in place.

This is a step that seems to always get overlooked when plumbing is done.
Few people strap or support the pipes.

thats exactly the problem! I may try that, but will probably end up re-plumbing the lines from that box with rigid pvc and move my unions/valves closer to the sump so I can get a magnet cleaner across the back glass.

My original thinking of ditching the box altogether was more along the lines of this drawing. May not be possible after all.

 

[K7BMG]

thats exactly the problem! I may try that, but will probably end up re-plumbing the lines from that box with rigid pvc and move my unions/valves closer to the sump so I can get a magnet cleaner across the back glass.

My original thinking of ditching the box altogether was more along the lines of this drawing. May not be possible after all.

I know you don't care about the noise, but I had a tank plumbed like this.
Yes could not control the noise and I never had good luck with sump levels.
I went to a back box and everything improved.
So IMO I think you will be going backwards to remove the box. YMMV

One thing I want to point out is fish can hear.
Noise IMO can have an effect on humans so I would gather noise could can have an effect on fish.

 

[gherewolf]

I know you don't care about the noise, but I had a tank plumbed like this.
Yes could not control the noise and I never had good luck with sump levels.
I went to a back box and everything improved.
So IMO I think you will be going backwards to remove the box. YMMV

One thing I want to point out is fish can hear.
Noise IMO can have an effect on humans so I would gather noise could can have an effect on fish.

Great point! Will need to design in a way to keep the box and mitigate the bending, like @K7BMG suggested.

I would also was to tint out the box because it’s clean now.....any suggestions?

 

[K7BMG]

Great point! Will need to design in a way to keep the box and mitigate the bending, like @K7BMG suggested.

I would also was to tint out the box because it’s clean now.....any suggestions?

Yes, just paint the outside black.