Fuel Tank issues

[280sleuro]

Hi everyone. My fuel pump in my 85 280SL started making a loud buzzing sound so I replaced the pump, but it also made noise. After checking the system I determinded it was a clogged before the pump. I removed the gas tank and found the outlet screen was clogged with red color gook. I cleaned the screen and tank till there was no sign of loose particles. This lasted about 100 miles before the pump started to buzz again. This time the screen was clogged with very fine particles. This screen is such a fine mesh it does'nt take much for it to clog. I took the tank to a shop that specializes in cleaning tanks. They acid and steamed cleaned it but was reluntant to coat the tank with sealer because they had a customer that had problems after coating his SL tank. My question is, has anyone had experience with cleaning and coating these tanks. I hear pros and cons about this process. I was also thinking of removing the screen inside the tank and installing an external filter before the pump .. any ideas.
Thanks, Jim