There are some enviro friendly water based rust removers on the market now, about $10 a Qrt..enough to do a tank easily., pour it in, swish around, once in a while over a 24 Hr period, rinse good with water, rust all gone. Run a vacuum hose in the tank to get some circulation 'til dry, then cream it, and add that inline filter, should cost about $50 total. Oh, then your a special tank guy.
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