Dirty sealant

[spud62]

My tank was bought second hand and the guy had resealed it, we have had no problems with it but just lately the sealant as started to blacken, do i reseal or will a good clean do it ?, thank you

 

[Chinadog]

It looks like the dirt is under the sealant, or maybe between the layers if its already been re sealed in the past. I've had the same problem with a tank that had been used for keeping gerbils. To get it looking clean again I used a razor blade to carefully remove the all the internal sealant beads one at a time and re did them with fresh silicone. Its best to do them one at a time because the tank would lose most of its strength and could easily come apart if the old sealant is removed all at once.