yeah, i've seen it but never used it, seen it in a nearest fish-store, they said it can be used in both saltwater and fresh water aquarium. u can use it to cycle and maintain an aquarium. it looked like a good water conditioner to me. u can try it.
Genie, I do use Stress Zyme, especially if I am going to do a big tank cleanup in my established tank. Sometimes if you really scrub decorations, vacuum the gravel, or rinse out your filters, it can cause a mini cycle, and stress the fish, I will add Cycle or Stress Zyme at these times to prevent this. However I would NOT put any one of these conditioners in a tank and think it is going to complete your new tank nitrogen cycle in a day! That just doesn't happen. It will speed the time to start the cycle and is helpful to have the bacteria to introduce into your tank, without just waiting for it to appear out of the air!
I wish you the best with your new tank, what FUN!!!
There have been lots of debates and mixed reviews of products like Stress Zyme and Cycle. From what I've gathered from several reviews in different forums, the bacteria in these products aren't the ones really needed to convert ammonia to nitrite, and nitrite to nitrate. But, the bacteria in these products are supposedly beneficial in helping to get the correct types of bacteria growing, so they may work in a sense, but unlike something like Bio-Spira (expensive & not available at many lfs) you can't expect them to get the cycle completed immediately. Give it time, and do the water testing to see when the cycle is complete - whether you do fish or fishless cycling. If the Stress Zyme works for you that's great! It did absolutely nothing for me to speed up my cycling, even after repeated doses. Once I added Bio-Spira everything went quickly.
The overwhelming amount of bacteria you need in a tank (supposedly 99.99%), are sessile - the opposite of mobile. That is, the bacteria adhere to all the surfaces of the tank, the gravel, decorations, and especially the surfaces of the filter bio media. Even if you take out all the water, 99% of the good bacteria remain because they adhere to these surfaces. And, so long as you don't let them dry out, they will remain alive and able to perform their cycling functions. That's why it doesn't matter when you do a water change, the bacteria remain. As long as you don't heavily vacuum the gravel, scrub everything down too much, replace all of the material in your filter at once, or mistakenly add chlorinated water, a product like this should not be necessary in a tank that's already cycled. IMO it's a waste of money to add it to an already cycled tank.
Edited because I can spell but can't type worth a darn!
Stress Zyme supposedly contains live bacteria, and I believe AquaSafe is just a dechlorinator/dechloraminator, with additives that help the bacteria, but doesn't contain the actual bacteria. From Tetra:
"All the features of today’s AquaSafe® now with BioExtract. The new formula now contains seaweed extracts (natural biopolymers) which support the development of beneficial filter bacteria for healthy and clear water. The added ingredients help to reduce aquarium pollution by strengthening the bacterial bed. As always, Tetra’s AquaSafe® water conditioner makes tap water safe for fish."
I have used all three. Bio spira, cycle, and stress zyme. None of them actually cycled a tank for me but I believe the Bio Spira whne I used it at the same time as cycle did speed it up for me. I set up a new 33 gallon L tank abut 2 weeks ago and my ammonia never got higher than .5 ppm and the nitrites never got higher than that either. It made it possible for me to add some Zebra Danios and the whole prossess was mostly done in the 2 weeks. It sped it up but didn't do the complete cycle for me. The stress zyme I have been using to help while I do water changes and I can't tell yet if it is helping or not. I pour it right on my rotating bio-wheel. I figure I would try it for a while and at least it doesn't hurt the fish.