Joining Dual Overflows?

[Jimbo7]

I just picked up a 210 that has dual overflows and I'm trying to find the best way to plumb everything.
I've been doing a lot of reading on the forums as well as on GMAC reef for tips. On the linked article, I would like to do option 2: where you link the overflows and then I can run a "split" beananimal style with 1 return as the last bulkhead.

My question is has anyone ever linked overflows inside the tank by drilling and siliconing in a PVC tube? I know it says in the article it will work, just looking for anyones examples or thoughts on how large a pipe I would need. I've seen a few people post about drilling and making a balance tube behind the tank but I'd rather not do that. See below for rough idea, thats the longest piece of PVC I had for demonstration. I'm planning on having around a 2" sand bed so the tube would be covered.

Any general thoughts on this?

 

[Matthew Frost]

I know people have done this with success but I would avoid punching a hole in the bottom of your overflow like that. Part of what keeps your tank from draining completely out in the event of an emergency is the fact that water can't get over the wier. If you don't get that silicone exactly right the water has a means to escape down to the level of your lowest drain and that could be bad.

 

[Jimbo7]

That's a really fair point. I think my silicone skills are pretty good but long term I wouldn't really want any issues. I might end up going towards option 3 and "disabling" one overflow.

 

[ca1ore]

The problem with balance tubes, other than the sealing issue on a curved plastic surface, is that the tube needs to be of adequate diameter to be able to balance significant volumes. I did one once through the back of each overflow and it required a 1 1/2” pipe to work properly. Trouble with just removing one overflow is getting acceptable surface skimming on a 6’ tank. Those dual overflows, whether aqueon or ML, stink. If I were you, I’d pull them both out, seal up the holes, and install a ghost-style overflow.

 

[Jimbo7]

Ideally, I'm with you on that. I'd much prefer to start from scratch and be able to drill and have a true bean.
Only issue is part of the deal struck to get a large tank in our main living room was that it be close to the wall and not have plumbing out and about.

I think you're right on the skimming, thoughts on bending a piece of acrylic and patching it into my one active overflow to increase surface skimming? See rough diagram below. I would cut a notch in the existing overflow and basically extend the weir out to help on surface skimming.