I did a 40% water change last night after not doing a water change for a month. I also changed the filter cartridges, but left the sponges in the filter. Generally I do water changes every two weeks. I also vacuumed my gravel for the first time ever, and turned up some blackened gravel, which, when vacuumed, gave off the smell of rotten eggs. I suspect it may have been anaerobic bacteria that I turned up. Now my tetras are darting around the tank, in particular chasing one tetra. Are they ill?
My water chemistry is also worrying. I have .5 ppm ammonia, and 0 nitrites and nitrates, so the tank seems uncycled again. There is also 1 ppm ammonia in my tap water.
1. Is there anything I can do to remove the ammonia from the tap water?
2. Would it help or hurt to do another water change at this point, and how much should I do?
3. How should I deal with the anaerobic bacteria in the gravel, if that's what it is?
4. I also have a bottle of Safe Start that I used to speed up my cycle the first time. Would it help the tank re-cycle quickly if I add that, and would that help my fish's symptoms?