Uniseals between sump tanks?

[jjohnwm]

Just stumbled upon this thread after searching "uniseal". How did this work for you? How's the longterm durability?

I am looking at using uniseals in exactly the same scenario as you, i.e. two adjacent tanks as close together as possible. I have had them set up this way for a couple years now without problems, utilizing a single bulkhead that stretches between the two and gasketing/siliconing both ends. However, one of the tanks has now developed a slow leak in one of the seams, which happens to be the seam sealing that drilled end piece to the tank. I can't help but think that the pressure applied to that glass by the tightening of the bulkhead has contributed to or caused this leak. Set up the way I have it, the end panels of those two tanks are both being pushed towards each other, and away from their respective tanks, by the tightened nut of the bulkhead.

I bought some uniseals and have been planning on replacing the single bulkhead with a couple of them, but now I am re-considering this plan. Your two-bulkhead idea looks appealing. The only benefit of the uniseals, as far as I can see, is perhaps a bit more flex and give, negating any slight misalignments of the two tanks. Your setup is really solid and rigid; those two tanks have to be perfectly straight/level/aligned. In a perfect world, mine would be...but the concrete floor in my basement fishroom ain't perfect...

Does anyone have any experience with uniseals that have been in use for extended periods, i.e. years? Do they hold up and remain watertight? They just seem like such a Mickey Mouse temporary idea...

 

[wednesday13]

Just stumbled upon this thread after searching "uniseal". How did this work for you? How's the longterm durability?

I am looking at using uniseals in exactly the same scenario as you, i.e. two adjacent tanks as close together as possible. I have had them set up this way for a couple years now without problems, utilizing a single bulkhead that stretches between the two and gasketing/siliconing both ends. However, one of the tanks has now developed a slow leak in one of the seams, which happens to be the seam sealing that drilled end piece to the tank. I can't help but think that the pressure applied to that glass by the tightening of the bulkhead has contributed to or caused this leak. Set up the way I have it, the end panels of those two tanks are both being pushed towards each other, and away from their respective tanks, by the tightened nut of the bulkhead.

I bought some uniseals and have been planning on replacing the single bulkhead with a couple of them, but now I am re-considering this plan. Your two-bulkhead idea looks appealing. The only benefit of the uniseals, as far as I can see, is perhaps a bit more flex and give, negating any slight misalignments of the two tanks. Your setup is really solid and rigid; those two tanks have to be perfectly straight/level/aligned. In a perfect world, mine would be...but the concrete floor in my basement fishroom ain't perfect...

Does anyone have any experience with uniseals that have been in use for extended periods, i.e. years? Do they hold up and remain watertight? They just seem like such a Mickey Mouse temporary idea...

Ive used uniseals for many years… they work very well IMO… used them on glass, acrylic, 55gal drums and even plastic totes. Their “downfall” is thin walled applications. Any material 3/8”-1/2” works excellent. 1/4” is even still good but they will leak on 1/8” plastic totes with not enough to make the compression seal. They do have some “play” in them like ur thinking also. Best example i currently have running is a uniseal in a bottom drilled 500gal tank. Its just 1” pvc capped off as i dont use the hole. 6-7 yrs running now holding back all that water ? lol… not a drop (knock on wood as always) ??…

 

[jjohnwm]

I've read about the downfall of larger uniseals with thinner tank walls. Would a 2-inch uniseal work with a 1/4-inch glass panel? I can't seem to locate a chart or reference that gives actual numbers rather than just vague warnings.

 

[wednesday13]

I've read about the downfall of larger uniseals with thinner tank walls. Would a 2-inch uniseal work with a 1/4-inch glass panel? I can't seem to locate a chart or reference that gives actual numbers rather than just vague warnings.

Ive mainly used uniseals for 1”-1.5” pvc… Will b a bit “hairy” to shove a 2” pipe into 1/4”glass (pucker effect) ?… but yes, it should seal up just fine. Most definitely use silicone grease to lube er up tho or u might crack the glass trying to shove the pipe through. There not that easy to put in without proper lubrication. U can squeak by with spitting on the uni’s with smaller diameter pipe or even use dish soap but the soap is a mess to rinse afterwards. Chamfering the pvc helps also. With the chamfer and lube u wont tear up the rubber and make the seal u need ??. Hope u know what im talking about with the silicone lube i may have the wrong name, its almost like Vaseline which would also work fine.

 

[jjohnwm]

Yeah, I know the stuff; I use it when jamming clear plastic hose onto barbed fittings in spots that are hard to reach. There are also some "1/2-inch" fittings that are actually closer to 5/8-inch, making the use of 1/2-inch hose possible but challenging. The lube is very useful there as well.

I'm familiar with the pucker effect also; not sure in this case if you mean puckering of the tank, i.e. breaking the glass...or the other kind...hopefully just the one in this case, rather than both...

 

[fishdance]

If you want two glass tanks as close together as possible, I would use silicon alone to bridge a gap up to 10mm. Even if you can get tanks closer, it's best to leave sufficient space to slide in a long knife (or embed some sacrificial fishing line) for future removal. If you want to bridge a wider gap, use a small rectangular glass box or cut top and bottom off a tall glass bottle. Consider using at least two holes before you join these tanks up as a single hole is easily clogged. Assuming 2 holes fit in your glass bottle - tube. Let me know if you need help cutting round bottles or free hand holes - curves in flat glass.

I have used uniseals but prefer only on larger diameter - 90mm ~ 150mm. Be careful not to break the tank glass when pushing the pipe through. It's more difficult to push through 2 consecutive holes than you might think. There is only one side you can push pipe through. Youtube for tips - chamfer pipe ends, diagonal cut, detergent to lubricate, F clamp to squeeze pipe diameter down, etc.

 

[jjohnwm]

If you want two glass tanks as close together as possible, I would use silicon alone to bridge a gap up to 10mm. Even if you can get tanks closer, it's best to leave sufficient space to slide in a long knife (or embed some sacrificial fishing line) for future removal. If you want to bridge a wider gap, use a small rectangular glass box or cut top and bottom off a tall glass bottle. Consider using at least two holes before you join these tanks up as a single hole is easily clogged. Assuming 2 holes fit in your glass bottle - tube. Let me know if you need help cutting round bottles or free hand holes - curves in flat glass.

I have used uniseals but prefer only on larger diameter - 90mm ~ 150mm. Be careful not to break the tank glass when pushing the pipe through. It's more difficult to push through 2 consecutive holes than you might think. There is only one side you can push pipe through. Youtube for tips - chamfer pipe ends, diagonal cut, detergent to lubricate, F clamp to squeeze pipe diameter down, etc.

I would dearly love to be able to butt these two tanks up against each other and just silicone the two panels together. However, there are issues with accessibility, space, etc. and also the fact that these are commercial tanks with plastic frames that prevents this. As it is now, the plastic frames are in contact, and the gap between the two glass panels is less than a half inch; my concern is that the pressure applied to the two panels by the single bulkhead is the cause of the leak. I'm thankful that a leak is the only result as opposed to an actual cracked end panel.

So...last night I re-sealed the interior seams of that leaker, and did it in a very experimental fashion; trying a new method/material so this is a good test case for me and for it. I also removed the bulkheads connecting these two tanks, and placed between the tanks a half-inch piece of plywood, roughly 12 x 12 inches, with a pair of 3-inch holes drilled to line up with the location of the two bulkheads. Pushed the tanks back together, reattached the bulkheads as before, and left it to sit and cure.

This enabled me to tighten the bulkheads much more tightly than before, but without any worries of this pressure flexing the glass and causing cracks or leaks. At this point, the only thing that concerns me is the Rube-Goldberg re-seal of the one tank.

This was all a PITA, due to the awkward location and access issues of the sump...but still much easier than struggling with inserting a short piece of pipe through two opposing uniseals, each mounted on a 100-pound aquarium with virtually no jiggle room. So I now have a few unused uniseals, just begging to be tried out.

Good thing that I am constitutionally incapable of leaving well enough alone...I'm sure I will think of something...