I have three Marineland tanks, two 90 corner overflow tanks and one 265g with dual corner overflows. Each one is well over 10 years old with black silicone and I’ve experienced zero issues. To be honest in the 40 plus years in the hobby I’ve only had one tank leak(I had a Stealth heater explode in an overflow which ruptured the back) and that wasn’t a failure of the tank. Maybe, I’ve just been very lucky.