I just resealed my first tank. Need help with overflow options.

[dbugg]

I recently purchased a used tank and finished resealing it. (It's been a long, dramatic story. If you want to read about it, it's here: https://www.reef2reef.com/threads/a...after-professional-move-what-do-i-do.1005503/ )

I had to remove the two overflow boxes for the reseal. It's now half full while I leak check it. Please see picture. Should I just reattach the overflow boxes? I worry about the fitment of the boxes to the tank due to the new silicone bead. Also the overflow boxes had a layer of glass under the acrylic. What are some considerations if you recommend just reattaching the overflow boxes?

What are my other options? Can I just use black pvc (the white pipes are just plugs for the leak test) and attach something to the drain standpipe and the return pipe at the top? (Should I worry about the stablity of the pvc/bulkheads if a rock was mishandled and made contact with the pipes?) Build some small new overflow out of acrylic for the top?

 

[DCR]

I don't think you want to just leave the standpipes like that as you would get very low noisy flow through just an open top vertical pipe. The easiest thing to do would be to reattach the old overflow boxes with silicon. You can trim the corners of the box if the reseal created too much silicon. It looks like it was originally a Durso with one drain and one return in each box which is not going to give you much flow without some noise. You could convert the original returns to a full siphon drain and make it into a Herbie. You would then need to change the returns to over the top or drill holes in the back for returns. Don't know if you have enough room in the back for piping behind the tank. Running two overflow boxes as a Herbie can be challenging to balance the flow between the two boxes. No experience but I have read this from others on this forum.

External overflow boxes like Modular Marine or Exotic Marine are popular as they do not take up as much space inside the tank, but you would have to drill the back of the tank and the tank has to be at least about 6" aways from the wall for the external overflows. Looking at your pictures that might be a problem and be difficult to access. Wrasses and clownfish always seem to get into mine. You would plug the bottom holes.

All things considered I would probably re-use the old overflows and either convert to Herbie's or leave as Durso's and live with a slightly lower return flow. I tend to think turnover rates of more than about 3 times per hour are probably unnecessary.

Edit: Looking at the reseal, you did not even have the U-bends on top of the overflow standpipes for a Durso. The open top pipes will be really noisy. You want a 180 U-bend (can be two 90 elbows) with an anti-siphon hole to make it quiet.

 

[dbugg]

I don't think you want to just leave the standpipes like that as you would get very low noisy flow through just an open top vertical pipe. The easiest thing to do would be to reattach the old overflow boxes with silicon. You can trim the corners of the box if the reseal created too much silicon. It looks like it was originally a Durso with one drain and one return in each box which is not going to give you much flow without some noise. You could convert the original returns to a full siphon drain and make it into a Herbie. You would then need to change the returns to over the top or drill holes in the back for returns. Don't know if you have enough room in the back for piping behind the tank. Running two overflow boxes as a Herbie can be challenging to balance the flow between the two boxes. No experience but I have read this from others on this forum.

External overflow boxes like Modular Marine or Exotic Marine are popular as they do not take up as much space inside the tank, but you would have to drill the back of the tank and the tank has to be at least about 6" aways from the wall for the external overflows. Looking at your pictures that might be a problem and be difficult to access. Wrasses and clownfish always seem to get into mine. You would plug the bottom holes.

All things considered I would probably re-use the old overflows and either convert to Herbie's or leave as Durso's and live with a slightly lower return flow. I tend to think turnover rates of more than about 3 times per hour are probably unnecessary.

Edit: Looking at the reseal, you did not even have the U-bends on top of the overflow standpipes for a Durso. The open top pipes will be really noisy. You want a 180 U-bend (can be two 90 elbows) with an anti-siphon hole to make it quiet.

Thank you so much for your help. As far as what was in the overflow boxes prior to my parting ways with my aquarium pro, I don't know. He had removed whatever was in the overflow boxes prior to moving the tank.

To add information, the tank will sit in a nook 3" from the back wall. Also, although I've drilled glass before, I'd rather not, and I don't have the room behind the tank anyway.

How can you tell there were no u-bends? The picture in this thread just has white pvc pipes acting as plugs for the leak test...

I will now google the hell out of "durso" and "herbie". Thanks again.

 

[DCR]

Thank you so much for your help. As far as what was in the overflow boxes prior to my parting ways with my aquarium pro, I don't know. He had removed whatever was in the overflow boxes prior to moving the tank.

To add information, the tank will sit in a nook 3" from the back wall. Also, although I've drilled glass before, I'd rather not, and I don't have the room behind the tank anyway.

How can you tell there were no u-bends? The picture in this thread just has white pvc pipes acting as plugs for the leak test...

I will now google the hell out of "durso" and "herbie". Thanks again.

There was one picture in the reseal thread looking down into the overflow box that just showed an open-ended drainpipe so I assumed there were no U-bends - although that would be really odd. There may well have originally been a 180-degree Durso connection on top of it. The box is fairly small so it may be a bit of a challenge to get the U-bend in there, but I think you can. I was going to add that those boxes are pretty small and will limit the flow due to the short weir length, so it is probably not worth the effort to do more than a Durso return pipe anyway.

 

[dbugg]

There was one picture in the reseal thread looking down into the overflow box that just showed an open-ended drainpipe so I assumed there were no U-bends - although that would be really odd. There may well have originally been a 180-degree Durso connection on top of it. The box is fairly small so it may be a bit of a challenge to get the U-bend in there, but I think you can. I was going to add that those boxes are pretty small and will limit the flow due to the short weir length, so it is probably not worth the effort to do more than a Durso return pipe anyway.

Oh, thank you for taking the time to look at the other thread. Yes that was his attempt at "patching and praying" and he had not finished with the pipes at the top of the overflow, so maybe he had intentions of installing a u bend.

I just read up on durso and herbie drains, and I'm following now. I have room to do over the top returns, and I like the herbie's emergency drain and loud noise when there's a problem. If l leave as dursos, there's just no emergency drain?? Maybe some limit switch in the sump that shuts off the pump? What do people do? Since I resealed this myself I want all of the failsafes I can find.

 

[DCR]

A Dusro does not give you an emergency drain but you would have two of them which is an added layer of protection. I have never really seen them fail unless you put a strainer on the end that can plug. If you push a lot of water through a Durso it will turn into a full siphon and really flow a lot of water so a single Durso should still prevent an overflow. That is what tends to make them gurgle when the flow is so much that it alternates between an open drain and a full siphon. I don't think you really need a high level pump shutdown, but you could include one if it gives you added comfort.

If you can go over the top, I think you might like the advantages of the Herbie. You need to make sure the return has a small anti-siphon hole, so it does not backflow and overflow your sump if the pump shuts down. You will also have to blank off the return ports out the side of the overflow boxes.

 

[DCR]

I would also recommend that you leave the test water in there for a while. I have never been able to successfully reseal a leaking tank without breaking all the panes apart and rebuilding it. If you did a good job of completely removing the old silicon bead down to bare glass it should work. I was generally too lazy to remove it all and that is probably what led to my resealing failures.

 

[dbugg]

I would also recommend that you leave the test water in there for a while. I have never been able to successfully reseal a leaking tank without breaking all the panes apart and rebuilding it. If you did a good job of completely removing the old silicon bead down to bare glass it should work. I was generally too lazy to remove it all and that is probably what led to my resealing failures.

Thanks again for taking time to help me. I'll think about Durso vs. Herbie. I thought a check valve protected the return from siphoning? Is a hole needed also? I am a former submariner, so I have a fondness for layers of backups.

And about the reseal, the more I read, it seems like everyone believes you have to completely disassemble the tank for every leak, but I'd like to know if the advice is from anecdotal or scientific evidence. If everyone used structural silicone instead of GE 1 and others, I wonder how many people would swear by a complete disassembly and rebuild.

Anyway I guess time will tell how well mine will hold. Hopefully I don't have additional evidence supporting complete disassembly.

 

[DCR]

I would not trust in a check valve alone to prevent a sump overflow. Sponges and other such things will grow on the inside walls of the pipe and valves and unless you routinely clean it out it will likely affect the ability of the check valve to seal. All you need is an 1/8" hole on the vertical down pipe just slightly below the water line at act as a siphon breaker.

If you did a good job of cleaning the glass of residual silicone the reseal should work. What does not work is applying silicone over old silicone. Just be aware that you have a leak path between the panes established so if the inside bead becomes compromised, it will leak again. Normally you want the silicone between the panes to be a tight seal. I would just give it a good long test to make sure it is holding before you start adding salt and gravel.

It is a nice looking tank you got. I also like to buy all my tanks used. I don't like them that deep just because it is difficult to reach to the bottom but there is no doubt that 30" deep tanks are very nice to look at.