Not a very strong one. The stronger the power, the darker the resolution and the harder it is to see what your looking at. Much like how a telespoce works, same deal. The power does not need to be all that high to see any parasites, be it worms or mites. I cannot remember off hand what we had at the hospital, but you could see results under the weakest resolution once you knew what it was your looking at.
Floatation tests are simple to do, and your average microscope is gonna do the trick. I would get familiar with the different parasites and what not by picking up some medical books. You can even do fecal tests on your other pets, if you have any that is. You can even do blood smears and other things like skin scrappings for other tests ideas to run. Microscopes allow more than the simple fecal floatation. Good idea you have to get one.