Originally Posted by Luggy978
Hi all. I've just been given a 15g tank with lights and filter. I'm going to start getting it set up and was wondering if it is worth using the old sponge to help with the cycle. Would this be achievable or should I get a new one and start from scratch?
One day at a time
If the sponge hasn't been kept in an established tank for a least a couple of weeks, it won't be any good. The good bacteria need food and oxygen to live. Without both, they don't live more than a few hours.
It would be best to start from the beginning and properly cycle this tank. You can cycle it with fish. This way you have activity in the tank right away. You can get 4 or 5 hardy fish like Platys or Danios and a floating plant like Hornwort. Set up the tank with gravel, light, heater, filter and a liquid water tester that tests for ammonia and nitrite.
If you want to go that route, then there's a procedure for cycling with fish. Just ask someone here.