I am having a problem with my water pressure getting low. I have a submersible pump and a bladder tank. The system has been in place since at least 1987 and I don't know any information on how deep the well is or what kind of batter tank I have. All I know is that its blue and is about 3 1/2 ft tall. I checked the pressure in the bladder tank and it had lost some pressure so I filled it back up. That was about 3 months ago. My pressure is starting to become pretty dismal again...until the pump kicks on and then its great. Sometimes I get little black flecks that come out of the faucet..but not consistantly. Is my tank bad or is my pump going.