WTF! Dude walk away from the deal! That jack hole advertised a reef ready tank and it is not reef ready. A reef ready tank is a premium tank that includes a mechanical filter, wet/dry, uv sterilizer, and usually an ozone system. All you add is live rock and corals. That dude only is selling a tank with a drilled overflow. Without the equipment, that tank is just another 55g tank. You can buy one new for that price at Walmart! And you will get a filter with it too! Don't spend more than a hundred bucks on a used 55.