how long does it take to cycle

IMO, 4 weeks minimum - and stay away from all the "instant cycle" crap you may see at your LFS or read about - it is all junk!
 
That really depends on a lot of things. Do you have any other tanks you can seed your new tank with? From the time I put water in my new tank (240) until the time I put my fish in was 2 weeks. I put my fish, corals everything in then. Although I do not recommend it if you've not done it before. I did have a 75 gallon that I tore down and used about half the live sand, about 3/4 of the water, all the live rock and then some. I'm telling you though if you've never done it wait! I also had a lot of help with other people giving me seed sand as well. In doing that you've really got to trust who you get your seeding media from too.
 
It all depends what you are using to cycle the tank. All new sand, water, and rock. Just sitting running won't do much. Getting rocks, or sand from other established tanks, and feeding the bacteria (starter fish, a chunk of salmon, etc) will decrease the amount of time it takes for a tank to be able to sustain a bio load.
 
Back
Top