I have the opportunity to pick up a used magnum 350 for $20. Guy told me it was used for about 3 months, then stored for 2-3 years because he upgraded to sump pum for his 125 gal tank. Is this a good deal. Look pretty used, but I suppose as will all used filters that have been stored for a while, the hard water and calcium build ups look a little nasty. Might be fine when its cleaned up. He said it comes with all the parts incl tubes. I know I should probably get new tubes. I mostly want this as a spare or for a 20 or 29 gal setup later on. What do you think?