To aerate my wort I have been using a whisk, but i am worried about contamination. What are other more effective ways to aerate wort without spending too much money?
When my boil's done and cooled, I pour it between the carboy and my bottling bucket a few times, making sure it gets well-splashed.
If you're doing a partial boil, you can often ignore aerating the wort, and just pour the extra water around to aerate, then add that to the wort in the fermenter.
According to Palmer, this will get you to about 8 ppm oxygen, which is on the lower end of the ideal range for most yeast (8-16ppm). That said, I haven't had any problem with it, and got a great fermentation on a 1.074 OG stout doing that just two days ago.
If you rack from your brew kettle to your fermentor with some tubing and racking cane you can get a wort disperser. These are little cone like things that go on the end of the tubbing and create a spray of wort as it enters the fermentor.
One of these combined with good ole' shaking in the carboy works pretty well for the cheap route.
If you want to do it cheap, with a canister of Bernz-O-Matic oxygen, a small regulator, and some aquarium stones from Wal-Mart you can do home oxygenation yourself.
Couple of caveats:
You must sanitize the aquarium stones. They will break down if left in One Step more than five minutes.
Throw out the aquarium stones when you are done. They are 1-batch use, no way to get them clean again after submersion in wort.
I invested in a stainless steel stone and oxygenate with it, it can be cleaned and boiled if necessary. A kit for this kind of think is usually around $35.00. I would skip the whole aquarium stone thing and just buy this kit. The little oxygen cylinders are cheap and last nearly forever, especially if you take the regulator off between uses. The whole kit is really not very expensive and I have found it helps fermentation more than our old splash method.
The whisk is fine. I've heard of using a collander before. All I do is dump the wort straight into the fermenter then repeat dumping water into it until filled enough. Ive been fine with it. Sometimes I'll whisk or shake if I don't feel it's enough. I typically stand by observing if bubbles seem to float in and on top of the beer then quickly pitch and seal up.