Tank was cycled, but now I'm not sure.

[I_Smell_Fish]

My 15 gallon tank was cycled and contained 1 male betta, 7 pygmy cories, and 1 nerite snail and water parameters of Ammonia 0, Nitrites 0, Nitrates 5.0. My betta died so I added 3 mollies with plans to add 3 more in a few weeks. Now my parameters read Ammonia 0, Nitrites .25, Nitrates 10.0.

One other thing I did yesterday was to remove the carbon from the filter and add PhosGuard to remove silicates that are causing diatoms. The instructions said to remove the carbon and leave the PhosGuard in place for at least 4 days.

Why the nitrites? What happened? How do I get rid of the nitrites?

Thank you in advance!

 

[Baker]

Well mollies produce a lot of waste, I'm not sure how much in comparison to a betta but I'm almost positive it's more. Seeing as how you added 3 your probably introducing higher levels of waste tha. Your tank was initially set up to handle.

You still have your BB so don't worry but you will need to monitor your ammonia until the BB has time to establish another round of young to take care of the excess levels

 

[Byron]

This is an identical thread to another [http://www.fishforums.net/threads/tank-was-cycled-but-now-im-not-sure.445006/ ] which can get confusing for members, so you might want to ask a mod to combine them. As I posted in the other, I will copy/paste here to have everything in both for the moment.

A 15g tank is insufficient space for mollies, so I recommend you return them. Mollies are not small fish, attaining 3 inches for males with females reaching 5 inches (6 inches is not uncommon). And as others noted, they have a significant impact on the bioload; being primarily vegetarian, they eat a lot and that means more waste.

Mollies should be housed in at least a 30-inch tank (like a 29g) but this is still pushing it and a 3-foot tank is preferable for healthy fish.

Byron.