My tank cycled but ammonia is still up. I know it’s cycled because I’ve been testing every day and have watched the ammonia rise and fall to about .5 ppm and the nitrates and ites rise and fall to zero. The problem is my ammonia is still at .5. I have two astrea snails in there right now, should I do a small water change? The tank is about two weeks old and I haven’t done one yet and the nitrates and nitrites have been zero for a few days now.