planning on leaving for a few days I want to make sure that my fish will be ok with one of those can someone tell me if they have ever used one and mabey if they do it will stop me from over feeding
The three day feeder blocks you can buy are fine. Temperature and hardnes of the water can affect the speed at which the food is released, i.e. the warmer the faster it is released.
I have heard of many cases where the feeder blocks can greatly drepreciate the quality of the water, to the point that some fish will die. I wouldn't use the feeder blocks if I ddin't absolutely have too, I woul try to get a mechanical feeder.