Okay sorry I'm totally insane, but I had a lull of time at work and did some googling...
And in case anyone doesn't want to spend a ton of money for epoxy resin or spend a month rinsing a DIY background, Plasti Dip is very inexpensive, comes in clear, and creates an impermeable, rubber-like seal coating. (No, I don't work for Plasti Dip.) I emailed the company, and they responded within a couple of hours to say the product is food-safe and freshwater aquarium-safe (they said they would get back to me about saltwater). It's completely non-toxic when dry and also flexible and has been tested from -30 F to 200 F. Unfortunately, I was raised in the states and they don't teach us how to convert to Celsius, but I think that would cover any temperature range for a fish tank lol. I'm going to check it out and will make a separate post once I do.
Don't know if it's available outside the U.S.
And in case anyone doesn't want to spend a ton of money for epoxy resin or spend a month rinsing a DIY background, Plasti Dip is very inexpensive, comes in clear, and creates an impermeable, rubber-like seal coating. (No, I don't work for Plasti Dip.) I emailed the company, and they responded within a couple of hours to say the product is food-safe and freshwater aquarium-safe (they said they would get back to me about saltwater). It's completely non-toxic when dry and also flexible and has been tested from -30 F to 200 F. Unfortunately, I was raised in the states and they don't teach us how to convert to Celsius, but I think that would cover any temperature range for a fish tank lol. I'm going to check it out and will make a separate post once I do.
Don't know if it's available outside the U.S.