I have had 2 Platys in my tank since Wednesday and I have just started testing the water myself (the pet shop was doing it before) and the first test I did was yesterday and I got a reading of 4.0ppm ammonia so I did a water change and got it down to 2ppm. I checked it again this morning and it was still 2ppm so I did another water change this afternoon and it came back out at 2ppm. Is this okay? I know it's not okay to have any ammonia at all but if I keep testing and doing daily water changes will it go down??