Frozen has always been accepted more readily than freeze dried foods IME.
I assume since fish generally are excited more by smell then anything that freeze dried foods aren't going to be as tantalizing to them since they tend to not smell as strong.
Food that isn't consumed quickly will just rot and increase your no3
which in turn increases algae.
I've tried tons of brands of pellet, flake, freeze dried, and frozen over the years and as long as the fish go after it with gusto I stick with it (assuming it is nutritional).
If worried about vitamin absorbtion you can always add Kent Garlic Extreme
, & Zoe
to help boost their immune.