Uniseals

[jd]

Hey guys, I'm getting everything together for my 20L and I've got a question. I'm doing an overflow like this one

[img[http://i434.photobucket.com/albums/qq68/Basilesim/65%20Montage/Photo023.jpg[/img]

And I was going to use a bulk head, but once it is in place, I won't be able to remove it as you can see. I was looking at MS and found some uniseals. I've never used them before. Do they tend to leak or slip? Would they work okaying in this setup?

[Blown76mav]

[CoralBeauties]

I have used quite a few uniseals.  Mainly in my skimmer and rubbermaid sump.  I would use them on a flexible material or a curved surface.  In a flat glass surface I would use bulkhead fittings like in Blown's pic.
The uniseal work great.  No leakage at all.  They are hard to shove the pvc through them when they are installed.  I have always applied a few drops of vegatable oil or dish soap to the pipe as I shove it through the uniseal.