[malawiMD]

I have just set up a new 90 gallon tank with a 20 gallon sump (about half full). When I set it up I used 40 pounds of live sand and seeded my filter with another used one. My water has been running for two weeks and I don't have any nitrates, nitrites or ammonia (Never spiked). When should I start adding fish, and how many small ones can I add?

Thanks

[Reefland]

What did you use the cycle the aquarium?

I would not add any fish for at least 2 more weeks. If you didn't add anything to cycle the aquarium (other than some filter media from another tank), I would drop a piece of dead shrimp in the aquarium and let it decay, watching ammonia and nitrite rise and fall during the decay.

[malawiMD]

I didn't use anything to cycle the tank. I assumed there would be enough detritus in the live sand.

Originally Posted by Reefland

What did you use the cycle the aquarium?

I would not add any fish for at least 2 more weeks. If you didn't add anything to cycle the aquarium (other than some filter media from another tank), I would drop a piece of dead shrimp in the aquarium and let it decay, watching ammonia and nitrite rise and fall during the decay.

[Reefland]

I would still add something to the tank to help it cycle, other than a fish. If you are not going to use any live rock, then a piece of dead shrimp from the grocery store would do the trick.

[Ninong]

Originally Posted by malawiMD

I have just set up a new 90 gallon tank with a 20 gallon sump (about half full). When I set it up I used 40 pounds of live sand and seeded my filter with another used one. My water has been running for two weeks and I don't have any nitrates, nitrites or ammonia (Never spiked). When should I start adding fish, and how many small ones can I add?

Thanks

You have only a very small population of beneficial bacteria at the present time because your setup did not have much in the way of nutrients (ammonia) to foster the growth of these bacterial populations. I agree with the suggestion that it would be a good idea to throw in a couple of raw shrimp from the supermarket and allow them to decay to generate the ammonia necessary to develop larger populations of bacteria. Your ammonia and nitrite readings will probably be back down to zero within about two weeks, assuming you already have a reasonable bacterial population density to consume the dead shrimp.

The alternative would be to add no more than one or two small hardy fish to your tank and wait a minimum of three to four weeks to allow the tank to balance itself before adding anything more.

[malawiMD]

Thanks for the advice Ninong and Reefland. I really appreciate it. As you can see from this and other q's I have asked, I am a beginner. I think I will try the tossing in a shrimp

By the way, this is a great site!

Originally Posted by Ninong

You have only a very small population of beneficial bacteria at the present time because your setup did not have much in the way of nutrients (ammonia) to foster the growth of these bacterial populations. I agree with the suggestion that it would be a good idea to throw in a couple of raw shrimp from the supermarket and allow them to decay to generate the ammonia necessary to develop larger populations of bacteria. Your ammonia and nitrite readings will probably be back down to zero within about two weeks, assuming you already have a reasonable bacterial population density to consume the dead shrimp.

The alternative would be to add no more than one or two small hardy fish to your tank and wait a minimum of three to four weeks to allow the tank to balance itself before adding anything more.