I"m so sorry for your loss Alysha. I apologize for getting his name wrong, of course I should have remembered his name was Edward, or at least checked the earlier post to be sure. I don't know why that name came to mind, but more importantly.... I'm so very sorry for the loss of your sweet frogs.
Be sure to really sanitize the tank. Read up on Chytrid, the fungus that may have been the problem. Most likely it was Red leg, but the flakiness you described is worrisome.
Chytrid is dreadfully contagious and it is necessary to use impecable technique to thoroughly decontaminate all equipment, tank, nets, buckets, filters, etc., to prevent your next frog from contracting this dreadful disease, if, in fact, Chytrid was part of the picture.
Since we don't know for sure if this was Chytrid, I would go on the assumption that it was, if I were you, and would proceed with the decontamination in the manner suggested in the information you find about Chytrid. Google it and you will find much information. If you have problems getting the information you need, just post again for help.
I'm so very sorry for your loss. RIP little froggies.