First tank, bought used. When can I add fish

[EllaMinnowPea]

This will be our first tank since I was a kid. Bought a 28 gal through Craigslist, used filter and used gravel included. Drained the day we picked it up.

Wondering about the nitrogen cycle in this situation. From what I'm reading the filter and gravel should be set with the needed bacteria. (Of course I don't know this, but the guy did seem knowledgable. Filter is definitely not new.) So would it be safe to slowly add a couple fish at a time while testing the water?

 

[Scottyhorse]

The filter's bacteria will most likely be dead now, so if you add a couple fish, you will do a fish-in cycle. Or, you can opt for a fishless cycle.

 

[bshenanagins]

The filter's bacteria will most likely be dead now, so if you add a couple fish, you will do a fish-in cycle. Or, you can opt for a fishless cycle.

Yeah once it's dry the bacteria is history. It's up to you if you want to cycle with fish. The other option is adding pure ammonia from the store. I've never done that method but many do.

 

[Fishperson]

The bacteria are probably dead if they are dry. Fishless cycles are easy and take less time, but there are no fish in the tank for a month. You just add pure ammonia to the tank to get it up to 4ppm, and then wait for it to drop down to 1, then get it up to 4 again, and keep repeating this. You should test every day. Watch to see when nitrite levels start to rise. Don't let nitrite get above 5, do a water change to lower it if that happens. Then wait until you can add 4 ppm of ammonia into the tank, and it will go from ammonia to nitrite to nitrate in 24 hours (so you go from 4ppm ammonia and 0 nitrite, to 0 ammonia and 0 nitrite). Then you are good. You should have around 80ppm of nitrates when you are done, but more is fine. Just do a water change to get it down to <40ppm.

 

[librarygirl]

If the filter and/or gravel dried out, it's probably useless in terms of bacteria for the cycle. If it's still wet it might help but it will also depends on how long it has gone without an ammonia source; bacteria need ammonia to feed on otherwise they die. You can proceed with a fish-in or fishless cycle; this article explains both: Guide to Starting a Freshwater Aquarium - Aquarium Advice

 

[EllaMinnowPea]

Filter was still wet, gravel partially as the bottom of the bucket had a little water in it from original owners. It was set up in our home the day before yesterday.

 

[librarygirl]

Filter was still wet, gravel partially as the bottom of the bucket had a little water in it from original owners. It was set up in our home the day before yesterday.

Wet is good. Do you know how long it has gone without fish? Fish provide ammonia which feed the bacteria, so it will depend on how long it has gone without an ammonia source. The safest thing to do would be to set up the tank and add some pure ammonia and see how long it takes to process. The link above I gave you has a fishless cycling guide that explains how to do this.