Oh how I know, everything has changed so much over the years. One thing here in Tulsa, they don't treat the water with chlorine or chloramimes but still use a water conditioner any way to help remove any metals that might be in the water.necessarily, it can be the water quality, not saying you have bad husbandry but the water is not what it was years ago.
If you pull the eggs and hatch in hydrogen perioxide bath and you get a great hatch out then you would want to investigate what might be wrong in the parents tanks.
I have some pairs that have parent raised for months then this winter everyone is having troubles. I generally will do a sanatizing of the tank and the parents to see if that takes care of the problem. PP is best but I have a color tint issue and it is safer for me to use the hydrogen perioxide