Join Date: Feb 2012
Location: Ontario, Canada
Your 2-4ppm of ammonia is great for cycling a tank. By the looks of your NO2/NO3 you're still in a very stage of cycling. I would suggest against any water change unless your ammonia goes over 5ppm at which level ammonia will actually start to kill the nitrifying bacteria.
If you don't change water, when your ammonia and nitrite (NO2) are at 0 ppm and you get a high reading on NO3, then do a 100% water change (preferably remineralized RO), let the tank run for another few days until PH is stabilized, then you are ready to add shrimps that requires soft and acidic water.