RODI filters

[justahobby]

I have one from buckeyefield supply which I'm pretty sure is the 100 gpd value series. I've had it for a little over a year and haven't changed any filters. Which ones need changing?

[Mike]

What is your TDS?

[justahobby]

Haven't tested it since I borrowed your meter, but it was between 1-2

[Europhyllia]

http://www.youtube.com/watch?v=himXj1MKTLc

[justahobby]

I hooked my guage up, turned the aqua on and it reads zero. So I guess the gauge isn't working....


11372

[CoryDude]

I picked up a replacement at HD in the water heater aisle. It was in the well pump section on that aisle.

Man, if anything, I'd at least change the micron and carbon filters. You're risking the tfc membrane if that carbon block is reaching it's limit. If anything, it'll help prolong the tfc's life. I'm guessing you're not making that much each month if your tds is still near zero.

I change my di resin if the tds starts to reach 4-6.

[justahobby]

How much were there, specs (micron, etc)? Thinking of ordering a sediment and carbon w/ the BRS group buy

[CoryDude]

I think I use the 1 micron sediment filter. As far as carbon blocks, just about anyone will do. I usually order which ever rated for the most gallons.

[justahobby]

Hm, didn't know you could get 1 micron at HD. Will keep that in mind for the future

[CoryDude]

Sorry, I was talking about the pressure guage not the pre-filters.

[justahobby]

Ohh Haha. Gotcha. I put it in the right spot, right? Between the filter and RO...

[CoryDude]

Yeah, I've got mine setup in the line that runs from the carbon filter to the ro membrane.

[Gseclipse02]

How much were there, specs (micron, etc)? Thinking of ordering a sediment and carbon w/ the BRS group buy


just buy the one they sell for 17$ or so comes with DI /carbon/ sed.

[justahobby]

just buy the one they sell for 17$ or so comes with DI /carbon/ sed.

That's the plan

[Gseclipse02]

cant beat that price

[justahobby]

Yep :D I was browsing their site when I saw their filters and it hit me that mine are probably due for a change.

[BuckeyeHydro]

A good rule of thumb is to replace your sediment filter and carbon block after six months. A more precise way to maximize the usable life of these two filters is to use a pressure gauge to identify when pressure reaching the membrane starts to decline. This is your indication one or both of the filters is beginning to clog.

Also be cognizant of the chlorine capacity of the carbon block. A good 0.5 micron carbon block for example will remove 99% of chlorine from 20,000 gallons of tap water presented at 1 gpm. Some original equipment suppliers commonly provide carbon cartridges rated at 2,000 to 6,000 gallons.

Regarding your RO membrane and DI resin, use your TDS meter to measure, record, and track the TDS (expressed in parts per million) in three places:
1. Tap water
2. After the RO but before the DI
3. After the DI.

The TDS in your tap water will likely range from about 50 ppm to upwards of 1000 parts per million (ppm). Common readings are 100 to 400 ppm. So for sake of discussion, let's say your tap water reads 400 ppm. That means that for every million parts of water, you have 400 parts of dissolved solids. How do we go about getting that TDS reading down to somewhere near zero?

If you do some experimenting with your TDS meter, you'll note that your sediment filter and carbon block filter (collectively called “prefilters”) do very little to remove dissolved solids. So with your tap water at 400 ppm, you can measure the water at the “in” port on your RO housing and you'll see it is still approximately 400 ppm.

The RO membrane is really the workhorse of the system. It removes most of the TDS, some membranes to a greater extent than others. For instance, 100 gpd Filmtec membranes have a rejection rate of 90% (i.e., they reject 90% of the dissolved solids in feed water). So the purified water coming from your 100 gpd membrane would be about 40 ppm (a 90% reduction). Filmtec 75 gpd (and below) membranes produce less purified water (aka “permeate”), but have a higher rejection rate (96 to 98%). The life span of a RO membrane is dependent upon how much water you run through it, and how dirty the water is. Membranes can function well for a year, two years, or more. To test the membrane, measure the total dissolved solids (TDS) in the water coming in to the membrane, and in the purified water (permeate) produced by the membrane. Compare that to the membrane’s advertised rejection rate, and to the same reading you recorded when the membrane was new. Membranes also commonly produce less water as their function declines.

After the RO membrane, water will flow to your DI housing. DI resin in good condition will reduce the 40 ppm water down to 0 or 1 ppm. When the DI output starts creeping up from 0 or 1 ppm, you know that your resin needs to be replaced. Sometimes people complain that their DI resin didn't last very long. Often the culprit is a malfunctioning RO membrane sending the DI resin “dirty” water. This will exhaust the resin quicker than would otherwise have been the case. Sometimes the problem is poor quality resin – remember that all resins are not created equal.
Russ