Well, I guess I actually didn't solve the problem.
I tested my water before and after changing it today. Before the water change, the ammonia was unusually high AGAIN at 0.5ppm. This time, the nitrates were still in check at their usual 5ppm. Nitrites were (and always are) at zero. After the water change, the ammonia's back down to the *almost* zero (0.0059ppm according to this
) that it was at the last time I updated.
I'm not entirely sure, but I think I might actually have a reason for the ammonia being so high this time. I was gone for a grand total of about five days. That's five days without me being here to turn my tank light on to give the plants the amount of light they need, which is usually somewhere around 8 to 10 hours. Needless to say, when I came back I had to do a little damage control because some of my plants were starting to die off and rot. Whether or not five days was enough to make nearly 0.5ppm of ammonia, I don't know but I suppose I'll know for sure next week (or possibly Thursday) when I do my water change ~