I purchased some of this the other day from Morebeer. It does clear the beer, the problem though is I have brewbuckets, force carbonate and need to harvest my yeast.
Seems like this is really made for conical tanks where you can drop the yeast first, then add.
First I tried putting silafine in to keg before carbonation (1 Tablespoon) - it never cleared. Must gave got caught in suspension somehow - and tasted grainy and super sludgy. Won't do that again.
Second try, I racked to a secondary first, crashed it and then added silafine. I also mixed it thoroughly (Ive read it has to be mixed really well) - I ended up using my Quickcarb without any C02, let it sit for about 24 hours. sort of a big pain. It did come out clear though and looked perty.
If I had a way to drop the yeast it would solve most all the issues. Hope this helps someone.