It was suggested to me that to get a jump-start on getting beneficial bacteria colonizing, you can purchase the bacteria (comes in a bottle)and then add it to you tank following the instructions on the bottle--keep filtration going, but don't turn on the light (at least that's what I was advised). But from what I understand, best way it to wait awhile before adding fish in a new tank and then pick hardy species to start off with. The bacteria will develop on their own. I would suggest danios or rosy barbs as great fish to "break in" a tank.

The best way is a fishless cycle useing generic amonia (free and clear type). If you know someone that has an established tank borrow some filter media to "seed" the beneficial bacteria. You can cycle a tank in a 2 days if you have enough seed material. (sometimes in a day)The only product that is proven effective that is bought off the shelf is "bio-spira" . It is hard to get at pet stores and is easier purchased on line. It is very expensive.Stuff like "Cycle" and "bio-zyme" are a waste. Another effective way is to do a planted tank. You need the right kind of lighting and substrate. Just set up the tank with live plants an when the plants start to grow well and are established you can start to stock the fish. Try joining this site for great advise and guidence with the fishless cycle. Plenty of comprehensive articles. If you want to cycle with fish be prepared for deaths. It can be brutal on even the hardiest fish. This all depends on water conditons.

Here is a link that might be useful: Try this

I am assumeing you are doing a fresh water set up. If saltwater then add live rock until it starts to flourish then stock fish.

The classic way is to stock it with a few hardy fish and let it cycle itself. This takes a while [big tanks could take 4-6 weeks]but works. Sometimes adding bacteria gives mixed results [how do you know if the bacteria is alive?]. Remember after it cycles to add fish slowly so the bacteria can adjust to the bioload. The cycle occures when the ammonia peaks to near lethal levels than drops to zero. Most freshwater fish are hardy so use cheap ones [zebra danios, guppies, plattys] in case they don't make the cycle.

Wow! i am so surprised by this forum - am new to gw but never expected to find a forum on aquariums here! woohoo! hope you guys dont mind me chiming in from time to time. i will post a new thread and intro myself.
as to cycling out a new tank, you didnt mention whether it is salt or fresh, but i would assume it would work much the same for fresh as salt. I have always found that adding just one hardy fish for 2-3 wks is sufficient to the task. i always add one fish at a time in order to insure my tank does not become 'infected' or if it does, i can pinpoint which fish intro'ed the problem and address fish and tank together....and gives me a good excuse to go shopping again the next week! lol
enjoy your new aquarium!
jo

Note that it's not just the ammonia that is deadly to fish; the cycle isn't really established until the nitrite level also drops to 0. The nitrite-eating bacteria don't get fully established until some time after the ammonia-eaters are working efficiently.

It's frustrating for beginners to see their fish die suddenly when they've got their ammonia level under control, because they weren't expecting the spike in the nitrite level that follows.

quite right ignoratio, quite right

I too tried fishless cycling and it worked very well.

I read to be cautious of some of the "bacteria in a bottle" products. Some don't actually contain any bacteria but do contain ingredients which supposedly encourage the growth of the beneficial bacteria.

Still, I read another source that says you can't buy beneficial bacteria in a bottle because the bacteria in question doesn't really have a 'dormant' stage where they can package it up and let it sit on a store shelf.

The bacteria does exists naturally in the air and water, but it's a matter of having it multiply fast enough to be able to handle fish waste in an aquarium.

Just my two cents.

Glen

Here is a link that might be useful: Fishless cycling

The only "bacteria in a bottle" that is truly bacteria, and can work is Bio-Spira by Marineland. However it is very expensive and hard to get. Better with filter media from a freinds aquarium or if the petstore where you buy the fish will part with some. Or buy a rock or ornament that is in the fishstores aquarium, and insist on the one thats in the tank. Sadly 99% fish stores will try to sell you the crap in the bottle. I think Cycle is actually nitrite. The others with "live bacteria" are crap. The bacteria wont surrvive on the shelf without refridgeration and only for a few days.

Well I have to say NEVER use filter media or ornaments from a pet store....think about this.....most pet stores have a high turn over of fish....comming in and going out. Sometimes fish have diseases when they come in and the disease is not detected before its sold.....then that means the fish can leave contamanents in the fish stores tank and water.......if you take water, filter media or an ornament from this tank......you will be asking for trouble in your new set up.

Now having said that.....some stores do have ways of dealing with these types of problems in their tanks....but most don't.

If you can get filter media or some aquarium water from a friend that you know hasn't had any problems...and hasn't added any new fish lately...then this is a good idea.

Also when you are purchasing fish...make sure to acclimatize them in the bag and then net the fish out into your tank......never dump that water into your tank.

Bacteria in a bottle is not a good idea......time and patience is what is needed to start a new system.