Micron size and rodi filters

[mfinn]

I've been looking around for a new rodi unit and have noticed a wide variety of differences in pre filter micron size.
Some places use 5 micron pre filters ( carbon and sediment ), some use 1 micron pre filters and some have .5 micron pre filters.
I would assume that the smaller the micron size, the better it protects the ro membrane.
I also see some of the popular vendors sell the 5 micron pre filters in their rodi units.

Is there not that big of a difference between .5 micron and 5 microns when it comes to rodi pre filters?

Is it better to have smaller or larger?

 

[Ocelaris]

Depends on your water quality coming in. Smaller pore size will clog the filter faster, but also remove more things so that the carbon filters don't have to. Also it's important to make the distinction between nominal and absolute micron. A nominal 1 micron is probably similar in capture capacity to an absolute 5 or 10 micron filter. So it's a trade off between clogging quicker cheap sediment filters VS replacing more expensive carbon, and even more expensive yet reverse osmosis membranes. I go with the brs line which is 1 micron on all filters, but I also have a 25 micron house filter and water softener ahead of my ro, so that takes the brunt of the sediment (which isn't much anyways).

Nominal VS absolute:

http://www.baldwinfilter.com/TechTips201403.html

Brs filters:

https://www.bulkreefsupply.com/brs-6-stage-ro-di-replacement-filter-kit.html

 

[mjlash22]

Depends on your water quality coming in. Smaller pore size will clog the filter faster, but also remove more things so that the carbon filters don't have to. Also it's important to make the distinction between nominal and absolute micron. A nominal 1 micron is probably similar in capture capacity to an absolute 5 or 10 micron filter. So it's a trade off between clogging quicker cheap sediment filters VS replacing more expensive carbon, and even more expensive yet reverse osmosis membranes. I go with the brs line which is 1 micron on all filters, but I also have a 25 micron house filter and water softener ahead of my ro, so that takes the brunt of the sediment (which isn't much anyways).

Nominal VS absolute:

http://www.baldwinfilter.com/TechTips201403.html

Brs filters:

https://www.bulkreefsupply.com/brs-6-stage-ro-di-replacement-filter-kit.html

I also use the BRS system/replacement filters. I have low TDS readings pre RO/DI so the 1 micron replacements work well for my situation. I have to replace about twice a year.