I will state up front that i have only used Vertex, but I have heard of problems with other brands but mine with Vertex. I have also heard the BRS product is better at removing phosphates. I really wonder if it matters, but whatever you chose go slow!!! All of the problems are related to adding too much to soon. IMO
i added them slowly over a 6 week course like everyone said, and i had a real bad cyano outbreak. since then I've bought a skimmer with a recirc mod, and i do a bunch of water changed just to stay ahead of the cyano, i didnt know if anyone has heard if any brand was directly related to such problems. thank you slapshot for sharing your knowledge thus far!!
So to my knowledge, it is a formula of plastic and really doesn't vary molecularly from brand to brand. Everyone I know who has used them gets an out break of "bad bacteria" initially. Which if you think about it is bound to happen. They feed bacteria, so the bad stuff gets fed too, just like in vodka dosing. Eventually when the phosphates and nitrates get used up, the bad stuff goes away and you are good to go. I used MB7 when I first started them and never got a huge bloom. Now I am starting them again, fresh, and am 2 weeks in still no bloom, again using MB7. Just a theory I have but when you dose MB7 or another Nitrifying bacteria while doing a carbon dosing of any kind you wont get the negative start up issues of bad blooms. (I don't know if anyone has proven that but it has worked for me.) I also did it with vodka and it worked there as well.