Another leak on a large tank

[Kmst80]

Water didn't hold with adding sealant over the existing seal.

I'm going to be most likely replacing this tank today. I found a local guy selling a 220 for $400 I'm hoping to pass by and take it today after work.

Silicone does not stick to silicone. You need to clean of 100% of the old silicone on both faces to successfully reseal a seam, 99% is not good enough. Only way is to take the tank apart.