For the StressCoat question:
Assuming for the moment we think of StressCoat as only a dechlorination/dechloramination product: Dechlor product overdosing has two "bits of lore" that I know of:
1) For mature tanks with a cycle that is mature, there is no problem with even large overdoses of a dechlor product and at times it can even be good when its use happens to coincide with the occassional overdoses of chlorine/chloramine by a water authority.
2) BUT, for fishless or fish-in still cycling tanks, there has been some concern (Hovanec, among others) that overdoses of dechlor product may inhibit N-Bac growth. My conclusion from that suspicion is that for people who are cycling, its much better to pay attention to the correct dosing per manufacturers instructions. I still feel its not necessary to be too exacting and that if you err, its better to err to the side of overdosing a little rather than underdosing, but people who are cycling might be wise not to just toss in large amounts.
As far as the "aloe" side of stresscoat goes, I've never paid attention to it or found it to be a problem. I've just ignored that aspect and used it as a dechlor product and it was fine. Most dechlor product discussions on TFF more recently have centered on cost and I changed to Prime because of these discussions, but now the leading edge seems to have moved on to some of the pond dechlor products which provide the same function at still lower cost.
For the StressZyme question: I agree with rabbut.
~~waterdrop~~