Hey!
You have two rather simple issues. One is the Magnum Power Kleen. If you would like to buy that, it may be at your local pet store, but they will most likely have to special order it for you. Tell them you want:
The Marineland Magnum Power Kleen...it might cost you about $11.
The other option might be a Python. This is a 25ft-100ft hose which connects to your sink and drains the tank, then fills it back up again. It'll set you back about $30-$50 bucks, but it's well worth it. Ask anyone with multiple tanks, (I have 6,) who owns one and they will say they can't live without it - I know I can't. The Python is probably a better idea, because the Magnum vacuum only cleans the water, it does not drain it. The debris will just rot in your Magnum until you clean it, and meanwhile your Magnum's flow rate will decline.