Can't believe nobody has answered you. Yes there was originally a filter in the tank. I know of nobody who still has it there. It's not metal but is made of a fine nylon mesh and yes, when it gets clogged, you'll have problems. The pickup line comes in from the left side then does a 90-degree turn. The filter is located at the bottom of the pickup line right at the plug on the bottom of the tank, so you will have to drain the tank. When you remove the old filter (it's cylindrical and about 3-inches long) do so VERY CAREFULLY!! Whatever you do don't bend the pickup line downward because then you'll have to push it back up into the tank to get the plug back in. When you do that you'll most likely put a crease (read split) in the line at the top of the tank which will then suck air when exposed (i.e. below about 7/8th of a tank). Then you'll REALLY have problems. Once the in-tank filter is out the external filter by the pump is plenty sufficient. Just remember to change it periodically. I normally do once a year. Keep 'um rolling.