If this is purely for aesthetics then sure, go ahead, just tape it up and be careful. If you are doing this for structural integrity then don't bother. The only way its going to do anything is if you drain the tank, cut the glass panels apart, scrape off all the silicone (I mean all of it, no residue at all), and then rebuild the tank. Some people scrape out 'most' of the silicone and squirt more in the gap without taking the whole thing apart but I personally feel this is pretty inadequate when going through the trouble of a tank reseal. Hopefully this is helpful.