kay-bee wrote:
Just to rule it out, test your tap water for ammonia levels. The chloramines
in my tap water register as 'ammonia'.

Thank you for all the comments. I think the pH did crash and possibly
killed all the beneficial bacteria. I tested my tap water before and
after adding water conditioner and didn't get any ammonia indication. I
think after the ph crash the dead plants may have contributed to the
ammonia increase. I will try to take a more "relaxed" attitude towards
my tank.