Sorry to disagree here, but I doubt it was a bacteria bloom unless you have added a whole bunch of bacteria from some source you havent explained (or I havent understood). In only a couple of days, you wouldnt have the time or the food source for this amount of cloudyness to come from bacteria.
I do think it is most likely from the substrate or maybe something from the decor that was not cleaned off first. In any case, zoe is right, dont worry. You will most likely see this a few times in the future.
How do you plan to cycle the tank? I highly suggest fishless cycling and you can read the pinned threads about how to do so in this thread (the beginners forum). This is by far the most ethical and less stressful on yourself since you wont have to worry about trying to keep anything alive. Otherwise, if you already know all of this stuff, I appologize for assuming that you needed help with getting started.
If you have more questions as to how to get your tank ready and able to support aquatic life, let us know. I think the tank looks great so far. I actually have the exact same set up. I like to keep the airstone opposite of the filter as well since this helps to aggitate the surface water more which will be the key for gas exchange (the bubbles from the airstone really do not add the oxygen to the water as much as one may think). Good job and good luck!
P.S. By the way, using the ammonia out chemicals are only going to slow down your ability to cycle the tank. You DO NOT want to use them and actually should be looking to add more ammonia since this will encourage the growth of the benificial bacteria (which will change ammonia in the form of fish wastes into nitrites and then into nitrates). These ammonia out chemicals/treatments are more to help an established tank when having a mini-cycle or to help save the life of fish when someone is doing a fishy cycle (which again, I do not suggest). In my opinion and experience, they are not worth the money or time and if you do things right, your tank will not need any chemicals to be added other than the dechlor conditioner you add to the tap water in order to take out the chlorine