Can Hard water cause my Angelfish eggs and fry to die

I have tried everything to find out why my Angelfish eggs and fry die. Many of them die about 48 hrs after they were laid and others of the same batch die after they become fry. The fry seem to be very weak and eventually die off. There were about 100 eggs or more and 4 fry have survived. I have tested my water and the PH is 6.5-7.0 but my hardness is about 180. Could they die from the hard water? Everything else is perfect.
Thanks!

It can't be lack of food. You don't feed them till they are free swiming. They die in the egg stage or the wiggle stage. It can't be poor stock because I have black angels from one oplace and Platinum from another. They are all from a fish Club that knows how to breed angels. We have used the water from the parents, day old water and some fresh with declore. Ive tested my water and even had the LFS test it and they say my water is fine for adults in our area. I thought maybe it could be to hard for babies.

I am not sure what predation is. I have looked it up and think what it means is there is another predator in my tank. What is the preditor? Is it a virus or a fungus in the water before the eggs were laid? How can that be. I am very clean with my tanks. I clean them once a week about 35%. and every 3 weeks 50%.