I see that 10" pre-filter sets vary considerably in price.
How important is that 3rd prefilter and are the more expensive Chlorplus or CBR2 worth the extra cost as opposed to the Carbon Block Chlorine Filter that Gardiners sell. Thanks.
i personally don't use the third pre filter never have, I have always used unnamed prefilters sediment and carbon block, I flush before every fill and my membrane has lasted years. I also have very hard water (high 400's) and don't use a water softner as that really just costed me money I was sold it buy a compnay that sells them it would cost alot more than a membrane would cost to replace which made it pointless, not always the case just in mine.
Keep it simple with what works perfectly well