Though you are treating your pets with flea treatment, you also have to treat the environment: your apartment. Any veterinarian office will be able to recommend a good one. Also, if you use the vet approved flea treatment for your pets, such as Advantage or Frontline, it will last for a month. Continue to treat your pets monthly until at least the first frost, then start up again in the spring. Fleas are probably coming in on you as well as your pets, so keeping your home flea proofed is important. Oh, and as far as I know, fleas and knats are two entirely different things.
Hagerstown