Boogi3man, as long as you don't add guanos or vertebrate manures, you should be ok in terms of the disease-causing organisms. Keeping the tea to its most basic form--worm castings and molasses, will keep you safe in that regard as long as you don't let the tea brew too long (longer than 48hrs, IIRC) and keep it well agitated and aerated.
Airstones clog VERY quickly and easily in this scenario, it's actually more effective to just weigh down the tubing and drop it into the bucket (I'm talking about quarter inch airline tubing, assuming you're talking about using an aquarium pump). The aquarium pumps I have, have two outlets, so I use two pieces weighted down for a 5gal bucket.
The thing with the Vortex brewers is that cone design, and it's not cheap to purchase in any event, not compared to something like a trash can that can be had for $15, give or take. That cone design does certain offer some positives, but requires an additional stand, so it is an investment no matter what route you take (purchasing the pre-made brewer or making one of your own), not the least of which is getting the tea back out of the brewer easily. Having the bad back as I do, those sorts of details can really make a difference.
I want to qualify my statements here: I have never used a Vortex brewer. I do make teas, so far only using aquarium pumps (multiple). I have scoped some of my teas, not all, and I have a hard time figuring out if what I'm seeing are eye floaties or bacteria. Hyphal strands are easier to make out, as are ciliates, protozoa and the like, but using a rather cheap scope makes ID that much more difficult. Plus, I could probably use a book right beside me when I do it. In any event, I just wanted to make sure that folks understand where I'm coming from here.