quarantining fish

[Ken Sauer]

For this particular tank, you need to work out why it still has ammonia. If there are plants in a tank, they will take up ammonia. if the tank had been cycled, the bacteria should remove the ammonia. And with no fish to make ammonia, there should be no ammonia. Unless there's something dead somewhere that's decomposing?

What is the sand? I know some types of soil can leach ammonia for months but not ordinary sand.

It's "aquarium sand" I bought at Petco... Nothing dead...

 

[mcordelia]

To diagnose your 10g, I think we have to start thinking about all the possibilities of what the source of ammonia could be (including a loss of beneficial bacteria). So a rundown of sources of ammonia could be: substrate (including pockets of stuff buried inside the substrate) - is it by chance meant for raising plants?; Something dead - have you checked the filter that there's nothing decomposing in there? All the nooks and crannies of the decorations?; Water - have you tested the water out of your tap? Does it by chance have ammonia?

The tank itself any cycling: how did you cycle the tank? (As detailed info as possible)

Do you use dechlorinator before or after you add the water to your tank?

Are you on well water?

I'm sure there are other possibilities, but let's explore these first.... And to your original question, I agree check out @HoldenOn 's thread. I now realize I added a video there that recommends treating prophylactically, I see the argument against it as well.

 

[Ken Sauer]

I finally just got rid of my sand substrate, bought Seachum Florite and a number of live plants. I'm starting over. Adding the bacteria start-up for 7 days. ( :