[bernawil]

> So when one times out, they all time out

Some units give you different fixed timespans for each. For that reason, I just use the Reverse Osmosis stage and ignore the rest. RO is the last step, and in theory it renders pure water meaning the only reason to have the previous ones is to pre-filter somewhat the water and extend the RO cartridge lifespan. Problem with that is, first, there's no way to gauge when each filter is spent. Second, they're priced the same anyway, so why even bother. Just go straight from tap to RO! Keep the post re-mineralization stage if you want.

[tguvot]

pre-filters typically have specified "capacity" in gallons. which is measurable. also if water is very dirty filters get clogged and pressure dropped. it's also measurable.

"post re-mineralization stage" is actually "ph adjustment".

[bernawil]

I know pressure drops. The problem is knowing which filter is the one causing it in particular. Also, filters that are spent at different rates are a PITA. What I mean is if you are going to feed it nominally clean tap water, there's no reason to protect a catridge with equally or more expensive cartridges. Just use the RO filter and be done with it.

[Xss3]

It isnt merely ph adjustment... You want some amount of minerals in water for your health, plants, and taste. Changing the PH isnt the concern in most cases, its just part of the result.