I just bought an MR-2, but the riser tube is 4in not the 6in that is stated on the website. I was told by the seller that they just changed the sizings and that it was stated on the MRC website, but i could not find that anywhere. All i want to know is if i actually paid for an MR-2 and hopefully not an MR-1. Also, if it is correct is it still rated for 300gal? Thanks