anyone else having trouble keeping german blue rams alive? i have a 29 gallon tank with 6 bolivian rams and 5 cory cats that have been in the tank for almost 2 years with no problems but every time i get a couple of the blue rams they always die. sometimes they live for a few months but usually die within acouple of weeks . i change 25 % water weekly. ph is 7.2 ammo and nites at 0 water is crystal clear . any ideas?