need help with my 20gal

[kmlong]

just have some questions. what is the big oil slick on the top of my water? Got my tank about 2 months ago, cycled it, have 9 fish in there, all doing fine and healthy. ammonia is at .5 though, fish have only been in a little over a week. I did not add them all at the same time, 3-4 a week. i guess the tank is still setting up cause the ammonia is still present. the end of the month will be the first water change. do i add the water right to the tank and then dechlorinate it or dechlorinate water in some buckets and then add? also, im hearing a lot of people saying not to even put carbon in the filter. I currently have carbon in right now, came with filters. that wouldn't be making the oil slick would it? is it bad to rinse your filter out under tap water. I try to get the most use from them till i replace. anyones help would be appreciated

[RogerMcAllen]

First off, if you have fish and ammonia, do a water change immediately. You definately arn't cycled, what method did you try?

Secondly, the carbon is not the cause of the oil slick, I know many [acronym:589d500367="Saltwater"]SW[/acronym:589d500367] guys have a problem like this, and it can be taken care of by dabbing the slick away with a paper towel. I think the cause might be a high level of disolved organics.

Third, put the dechlor into the water, then add it.

Fourth, it is bad to rinse your filter in tap water. When you are doing your water change, wash out your filter in the old tank water. This will keep your bacteria alive. Have you washed your filter out completely in tap water since your cycle? If so, this could be the reason your tank is cycling now.

Lastly, what kind of fish do you have?

[Endgame319]

You should be doing weekly or bi-weekly 15-50% water changes. Once every few months is not enough. The oil slick is a protien film. Its not bad, and some fish actually eat it. If you dont want it you can remove it with a paper towl (make sure that crap wont come off the towel into the water). And carbon in your filter does help keep the water crystal clear, but it isn't necessary. And you have to change it every month. And yes it is bad to rinse your filter in tap water. It kills the good bacteria you need. This is why you still have ammonia in your tank when it should be cycled. Rinse media off in dechlorinated water or tank water. I dechlorinate teh water before adding it to the tank, because when you dechlorinate after, your exposing your fish to chlorine. It may not be fatal, but it can be stressful.

*Edit* Looks like you beat me by a few seconds roger

[Devilishturtles]

Carbon is a good thing to have, but loses it's effectiveness rather quickly. There is the lifelong debate that will always go on about if carbon is needed or not. The oil could be from something you put into the tank that is new? How long have you noticed the slime? Add anything new lately?

Also, you can rinse your filter under tap water if you already have dechlorinated water. If not..and I am assuming that you don't since you asked about decholorinator, get a bucket of your tank water and rinse in that..the chlorine will kill all your beneficial bacteria.

[acronym:a2c2b389e0="Hope this helps (or) Happy to help"]HTH[/acronym:a2c2b389e0]