Sealing plastic rim on tank

[Moncrief2315]

Hi. I recently noticed my tank had streaks of water on the front and looked up at the top and it was dripping water from the rim. The water level is just below the rim. When I push up a little bit it moved up. Not much but enough for water to get behind it. I want to seal it from the inside. It’s only about 3 or 4 inches of it that moves. Now how would I do this with my fish still in the tank and what’s the best silicone to use that’s aquarium safe. Obviously I know I have to remove some of the water but do I have to remove the fish if I’m sealing it from inside? Thanks all.

 

[Autumnsky]

Silicone takes about a week to dry and needs to be dry to cure.

Aqueon makes black and clear sealant in smallish tubes I think 3 ounces and I found some clear in the big box store.

GE Silicone 1 Window and Door must be the #1 type because it doesn't have the mildew stuff which isn't aquarium safe.

You could lower the water level, and if there is any splash type areas you could use packing tape to tape on something plastic like trash bag or vinyl report covers to keep the water off of it. If you can smell the vinegar like smell from it it isn't cured. I haven't done this on my own tank with fish in it but I wouldn't be worried unless they were super delicate and super expensive fish.

Do the work on a nice warm day to allow good ventilation and the outer coat to dry quickly, maybe even a fan if you have one. To counteract the moisture of the tank evap.

Precautions should be taken to not allow and of the silicone globs to fall into the water.

My opinion is I would try it with the fish in. But you could always remove them to a plastic tote or 2. Catching them would be a pain though (and a bit stressful).

Maybe someone has actually done this, fish in tank to give actual experience.

Good luck with your project. Having water dripping out of the rim is not ideal.

 

[Andy Sager]

If the rim is loose, you can remove it and put a thin layer of silicone inside the track of the rim that the glass fits into so that the entire lid is sealed and water cannot get underneath the lip when you put it back on.
If you cannot remove the lip, lower your water level and wearing a glove ( or moisten your finger) and add a small amount of silicone to your finger then run your finger under the lip, adding more silicone as you go, so that you seal the whole lip from the inside. With a glove, you keep yourself from getting sticky. If you don't use a glove, moistening your finger will help keep the silicone from sticking to your finger. For whatever does stick, I let it dry then it rolls off the fingers more easily.
As for which silicone to use, you may have to look at what you have available in Canada. GE makes a silicone that explicitly states " safe for aquariums" . I get mine at Home Depot in the U.S.
As previously stated, you want to do this on a day where you can get a lot of fresh air circulation because there will be a smell that can be overbaring to some. You also want to keep the area you silicone dry for 24 hours so it has time to cure. That may mean leaving the water level low in the tank for 24 hours after gluing.