How fine should the filters be in your RO?

[percula99]

I want to replace the sediment and carbon filters in my RO unit. Do I need to use 1 micron or 5 micron filters. I am having an issue with water pressure. I am only get 40 psi but that might be just because of where I am located in my city. Will 1 micron filters reduce the pressure and will 5 microns give me good enough water quality?

[gweston]

My current system is: (from airwaterice)

10 micron sediment
5 micron carbon 1
1 micron carbon 2
Filmtec 75gpd 98% rejection membrane
DI - color changing resin.

I have seen some places sell their sediment filters at 5 or even 1 micron. I'd think for a 5 stage (as noted) RODI Unit.. 5 micron is fine. The subsequent filters will catch anything in the 1-5 micron range. One filter set I am looking at next is: (from BRS)

5 micron sediment
5 micron carbon 1
1 micron carbon 2
DI resin.

Basically you nudge it down to 1 micron through multiple filters, it then hits the membrane, and then a final scrubbing with the DI. I'd think a 1 micron sediment would clog notably faster than a 10 micron one. But if you do use a 10 micron, you just end up scrubbing out the larger particles in the subsequent filters anyway.

You may want to check your pressure before the RODI Unit. I forget what the suggested pressure should be. It can depend on the unit/filters, but the typical min/max range seems to be between ~45-80psi. The system will work less efficiently if the pressure isn't adequate. There are pumps to up the pressure before it enters the RODI unit, though they can cost a good chunk.

Y

[AM916]

I have the 5 stage deluxe from BRS. I use 5 micron sediment to 5 micron carbon to 1 micron carbon. It works fine that way. If you use 1 micron sediment, it might clogg up faster and decrease the psi. I am on well water though, city water should have a lot less sediment in it.

[percula99]

I have a Kent 50 GPD three stage RO (sediment, carbon, membrane) but I have added a dual stage chloramine pre filter and a DI at the end making it a six stage RO system. I get a TDS reading of 0 and have had since upgrading. Kent recommends a 1 micron sediment filter, but that is for the original configuration before my add ons. My city's web site says pressure is different depending on what part of the city you live in. Some people will get between 35-45, and some will get between 60-80. I am getting 40. I hope changing the filters will help add some pressure, if not a booster pump may be in order. I am really tired of seeing so much water going down the drain.

[Buckeye Hydro]

Originally Posted by gweston

Basically you nudge it down to 1 micron through multiple filters, it then hits the membrane, and then a final scrubbing with the DI.

This is a good approach, but applies ONLY to sediment filters. The pore size of the carbon block(s) should be about the same or larger than the smallest pore size on your sediment filter(s).

So this is OK:
10 mic sed
5 mic sed
5 mic carbon

or
1 mic sed
0.5 mic carbon


Avoid something like this, as it has the carbon blocks functioning as sediment filters:
10 mic sediment
5 mic carbon
1 mic carbon

Russ

[percula99]

Originally Posted by gweston

You may want to check your pressure before the RODI Unit. I forget what the suggested pressure should be. It can depend on the unit/filters, but the typical min/max range seems to be between ~45-80psi. The system will work less efficiently if the pressure isn't adequate. There are pumps to up the pressure before it enters the RODI unit, though they can cost a good chunk.

My pressure has fallen to about 30 psi now after the dual chloramine filters, sediment and carbon filters. I checked the pressure coming into the system before any of the filters and was astonished to see it reading 75 psi. I am losing more than half of my pressure just going through the filters before the membrane.

[percula99]

Originally Posted by BuckeyeFS

This is a good approach, but applies ONLY to sediment filters. The pore size of the carbon block(s) should be about the same or larger than the smallest pore size on your sediment filter(s).

So this is OK:
10 mic sed
5 mic sed
5 mic carbon

or
1 mic sed
0.5 mic carbon


Avoid something like this, as it has the carbon blocks functioning as sediment filters:
10 mic sediment
5 mic carbon
1 mic carbon

Russ

I have an order coming in from BRS scheduled for delivery by UPS on Thursday. I can hardly wait to get it in because I really need to make the change. I ordered the 5 Micron Purtrex Depth Sediment Filter and the 1 Micron MATRIKX® +1 Carbon Block .

[Buckeye Hydro]

Originally Posted by percula99

I ordered the 5 Micron Purtrex Depth Sediment Filter and the 1 Micron MATRIKX® +1 Carbon Block .

We'd never recommend that combination to you.

Russ

[percula99]

Originally Posted by BuckeyeFS

We'd never recommend that combination to you.

Russ

Why is that Russ? By the way, no one at BRS recommended these filters, they are just what they had. My Kent RO unit recommends a 1 micron sediment filter but a friend of mine told me a 5 micron would not clog up as fast and would not reduce the pressure as much. Is that incorrect?

[Buckeye Hydro]

Check out my first post in the thread.

It is true that a 5 mic sed filter won't clog as fast - but that is because it is not catching as much of the sediment as a 1 mic. Using that logic, you might conclude that a 20 mic sediment filter would be better yet. If you have found that a 1 mic clogs too fast for you, then you might want to consider:
*5 mic sed and 5 mic carbon, or
*5 mic sed, 1 mic sed, 0.5 mic carbon

Russ

[percula99]

I am not really overly concerned about how fast the filters will clog. I am also confident with a six stage RO that my water is coming out clean enough as my reading is 0 TDS after the DI stage. My real concern is the drop in pressure I am experiencing and what will return me to a higher pressure entering the membrane. I am wasting way too much water down the drain.

[Buckeye Hydro]

It is the clogging that is robbing you of pressure.

First, use filters with the correct pore size as I went through above. Once you do that, if your pressure is too low, change the filters if they are logged, or if they're not clogged, then consider a booster pump.

Russ

[Lemeshianos]

Just wanted to post a thanks to Russ. I'll be changing prefilters soon and your posts were quite helpful. If shipping from USA to Cyprus didn't cost an arm and a leg, I would gladly buy from you.