yeah i would go ahead and do waterchange, im on tap as well and when i was raising festae fry i was doing 50% waterchanges every other day and they were fine, its not a problem as long as your tap pH is the same as your tank pH and your not using like a pH balancer or anything, also does that aquasafe stuff protect against chloramines as well or just chlorine? i use prime as my dechlorinator as it gets rid of chlorine, chloramines and any ammonia that might be in your tap. since its something they both did then im thinking its probably something to do with your tap water but yeah if the nitrates climb above 20 within the week then you should do more than just 1 weekly water change to try and keep it below that, GOOD LUCK