I have dealt with the problem - Jack (my red betta) had it, or something very similar to it. I treated him successfully with both meds.
The bleaching of a glass tank is perfectly safe, if done correctly - the tank that Jasper and Charlie are both in right now were done that way and went into them less than 30 minutes after they were rinsed out. Several people on this forum have bleached their tanks this way. I was nervous about it the first time I tried it also, but it works. If you rinse them properly you have nothing to worry about.
But, if you choose to wait til someone else gives you some advice, I respect that.
Good luck with your girls.