IF you went most of a year not de-chlorinating your water you are going to loose fish like crazy because every time you add the chlorine it wipes out any BB and is horrible for your fish. Throw in loads of snails that are also likely dieing from the chlorine as well and you would have ammonia bombs everywhere.
ya may have stabilized it over the last 3 months of de-chlorinateing it. so you wont have losses like you did but I would put most of your losses on chlorine and no BB because of it.