I have a 20 gallon tank that I have transfered my fish form a 10 gallon "storage tank" (I recently moved and couldn't bring a great deal of water with me) I have transfered over my filter, some gravel, and about 70% of the water out of the 10 gallon. I really need to change my filter media (I already changed my carbon because it was WAY too old) How long should I wait before changing at least one of my other pieces of media?
