I'd appreciate any help with this. I have a 275-gal aboveground outdoor oil tank. This heating season I've been having problems -- first the whistle on the tank apparently goes off when the tank is only half full so the oil company thought it was a full fill-up and the tank went dry. Since then it's been a headache -- within a couple of days the furnace sounded like it was throbbing (?). I initially thought the line was frozen or freezing (I had this happen my first winter -- I didn't know about the anti-gel you need to add to the fuel) but I had added the anti-gel when the tank was filled. The service tech blew whatever it was in the line back into the tank and changed the nozzle. Two days later, it happened again. and again. then fine until . . . the tank was next filled. same thing all over again. I've been told it was frozen water in the line or sludge from the bottom of the oil tank. One technician (I think I know all of them by first name basis now) said that condensation from the sun beating down on it during the summer leads to bacteria growing in the tank and that's the sludge on the bottom. I also read that condensation leads to corrosion and that's the sludge. so apparently when the tank gets filled the sludge gets stirred up then as it settles everything's ok. Does this sound right? I've been told I should replace the tank with a new one. Is this the only solution? I've seen these plastic enclosures for outside tanks -- would that reduce the condensation?
Thank you very much for your help!