Aquariums.

Leaks.

Two words you don't ever want to use in the same sentence.

I have an overhead sump on the top of my aquarium that's been in place for several years now, utilizing a window box planter with holes drilled in each end,
with a Uniseal/PVC fitting that the water flows through.

For a while I've noticed a periodic seeping that comes and goes at one of the drilled ends.
After making an adjustment the other day I started noticing some more dampness - just a very slow drip, not too much.
But a drip.
Today I decided I really needed to look into it further, because this time it wasn't going away.

The Uniseal had completely torn open on the inside (the side that's in contact with the aquarium water),
and the tear had finally started to migrate to the outside - hence the drip.

Furthermore, upon investigating the other seal, it was blown out exactly the same way.
Fortunately I had spares. Unfortunately, this required draining, cleaning, and dismantling the sump entirely, and the Uniseals are a bit of a beast to install. Took about four hours.

Looking at the bright side, it wasn't a sudden, catastrophic failure, and it happened in daylight, and I was here.
It feels unlucky that it happened, but really it's quite lucky that it didn't blow right after leaving for vacation somewhere - while it sucked, things went wrong in the right way.

I guess.

Here's a picture of the seal: