Which method is best to cycle

[aws2266]

I'm going to be setting up a 120g in a couple of weeks and am wondering what's gonna be the best method to cycle it? I have a 55g and was thinking of doing 30% water change and putting the old water in the new tank. I can also get a bunch of saltwater mollies at my LFS for cheap. Then there's the bottled bacteria. I'm leaning towards using the old water and grabbing a few saltwater mollies. Looking for feedback and possibly how many mollies I should put in to effectively cycle a tank that size?

 

[Quietman]

I'm going to be setting up a 120g in a couple of weeks and am wondering what's gonna be the best method to cycle it? I have a 55g and was thinking of doing 30% water change and putting the old water in the new tank. I can also get a bunch of saltwater mollies at my LFS for cheap. Then there's the bottled bacteria. I'm leaning towards using the old water and grabbing a few saltwater mollies. Looking for feedback and possibly how many mollies I should put in to effectively cycle a tank that size?

That'll do nicely. There's infinite startup (cycling) methods and oddly enough they all work. The nitrogen cycle is one of those inevitable process that you really couldn't stop if you tried. The important part is that you're aware of it and are taking steps to make sure your tank is ready.

I'd add one or two. Then add your full load slowly after a couple weeks. Shouldn't take long at all with old water. Even with new water, one or two mollies is unlikely to hit harmful ammonia levels in a 120 gallon tank.