House nuetralizer HELP

Hi, All,
I have lived in my current house located in South East Pennsylvania,for about five years. It has well water with neutralizer on it. There was no documentation on the water treatment system that came with the house .It is the first and only house I have ever owned or dealt with that has a well. Today I removed the neutralizer tank and cleaned it out and flushed it .Now the problem. The house came with a HUGE bag of marble mix. After I cleaned out the resin tank, I put it back in line and proceeded to fill it almost 3/4 of the way up with marble mix ONLY ( I said I had a HUGE bag of it ). After I back flushed it and was feeling all great about what I did, I saw my neighbor and told him what I did. He said "you can't do that because there is sand and gravel in the bottom of a neutralizer, and the marble mix goes on top " .He owns a Sears unit .We looked at the owners manual .It also sound right because of the composition of the muddy sludge that came out of mine. Well , ..... He is right, BUT, what are the ramifications of leaving the mix in the whole thing? Will I poison the family? Is it a matter of cost? If I had to BUY that much mix, it would cost about $150. If I HAVE to empty it and refill it, does anybody know exactly what kind of sand and gravel to use? The thing hasn't worked right in years, and now its all running properly, hopefully in time to save my copper pipes .The water is not cloudy. Up until now, it could turn a white tub aqua blue in a week, though .
Thanks for any and all responses ,
Jerry .
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