Question on Potential Plumbing Disaster

[NewRobert]

Hi All,

I bought a second hand cube. While I will be waiting for the refinished cabinet's paint to cure this week I would like to get the display-tank sorted out so long as the silicone is going to take at least 7 days to cure as well.

(You can see the thing here: https://www.reef2reef.com/threads/roberts-180l-rescue.807270/#post-8648585)

Please see a picture I took of the overflow-box that has already been plumbed. Obviously the plumbing was leaking when I got it (judging by the thick rings of silicone I cut off with a razor blade). I plan to take all the plumbing out and redo it from scratch.

Here is my question: Isn't this tank going to drain almost entirely into the sump if the return pumps stop for any reason with that pipe so low in the overflow box? By my crude grasp of where and how water flows, what they had there doesn't make any sense to me whatsoever? It may have been fine if the overflow box didn't have the open grating in the bottom as well not so?

Am I missing something?

The returns were just siliconed in place - and obviously was leaking at some point. I plan to remove all the pvc as well as the black plastic sheet, clean up the silicone everywhere, re-silicone the plastic backing back in (ensuring tight seal around the return holes) and replace the returns with bulk-heads and also do the same for the drain/overflow box. I was thinking the only way to avoid disaster of the entire tank draining into the sump in the event of a power-out or pump-fail would be to bring the pipe coming up the overflow box all the way to the top.

Right? Am I misunderstanding some physics here?

Thanks in advance

 

[CK00020]

I think you are right, that’s a weird overflow. I have seen some like it before but never that low.

 

[CK00020]

I dont think the last guy plumbed it right, the pipe should come up closer to the top

 

[CK00020]

It had to be one noisy sob

 

[mdb_talon]

Ya looks like poor design. As you say without that bottom grate it would be fine other than probably loud...with it though is waiting for a big mess.

 

[NewRobert]

Please excuse me. I am an idiot. There is a baffle there... that I missed... somehow...

I just took of the plastic sheet at the back.

Now I feel like a twit.

So now here is more questions:

1. With this new information, should I still keep it that low or raise it to the top?

2. The returns, seem kind of low - I cannot see how this is not going to cause a syphon when the pumps stop. I was thinking adding a elbow to bring them up and another elbow to direct the flow back forwards. Yes / No? No good?

Thoughts?

 

[mdb_talon]

I was wondering if there was baffle but saw light through it in picture.

As for returns from the pic it looks to me they will start sucking air about same level as that overflow so seems that just gonna be the level?

I would put a taller standpipe on just seems that would he loud...might be wrong though

 

[NewRobert]

Yes the overflow is the same level as the returns. I realize the problem now, it is quite low for a water-line on a rimless tank. It is 2" off the top. My 100gal has only got about 1" of glass above the water-line but that has a humongous canopy covering it. I suppose the first prize would be to get the tank running and I can see if I want to up the water-line later.

How do the rim-less guys usually do this? I assume I am not alone with not liking the idea of 2" of glass above the water?