RO System Replacement Filters
 

I assume that out of all the stages in my 4 stage RO system, that the membrane is the most important?

I'm wondering which one to replace first, as they are fairly expensive, and breaking them up over a couple different purchases would be a lot easier on the pocketbook.

Thoughts?

I figure that unless your TDS is going up then a regular switch of the cheap filters is all you need. Some people get a year out of their membranes. I'm lucky to get six months due to the high solid content in our water.

Actually I find that replacing all of the cartridges is the best solution, and they are not that expensive. I have been buying them from Kevin @ Red Coral and the pricing is quite low.

Now I don't run DI, so I can't say what cost is there, but carbon, media filter and membrane was like $30 or so bucks for everything from Kevin.