Yes, I have 2 trochus from this site, and they are the size of a golf ball...and getting bigger
You should not overpopulate with these snails. Big snails, means big appetite and wo the specific foods they require, they will not live. I was only able to maintain 2 large ones in my 72gal, the rest died wo a sufficient food source.
As for trouhus eating cyano, if there is some in the places that they like to eat, like rocks or glass, yeah they will catch some of it. However, these snails are not sand snails, so they aren't going to help with sand cyano. Also, their food source is mostly diatoms.
I emailed Boyd Enterprises about their product ChemiClean which is supposed to get rid of cyano. They wouldn't tell me what their ingredients are, but did say that their product is not an antibiotic [which will also kill cyano] and it is reef safe. They also said that it is important when dosing to go by the actual gals of water in the tank, not gal size of the tank, otherwise you could overdose.
I've always had a bit of cyano which I never worried about, but about a mo ago I had an almost overnite bloom erupt in my reef tank. Likely this occurred due to my having switched my water source [which did have a trace of phosphates] in addition to making several organism additions to my tank. I've added 2 PH's, added an additional 20lbs of LS to try and clear up the problem. I've also used a turkey baster to blast off cyano from my rocks so that it could be picked up by the skimmer. Its taken time, usually several "cleaning" activities a day, but the situation is coming under control at this point.
I also added Nassarius snails which are great to get that DSB turned over, as well as some ceriths, which are supposed to eat cyano.
