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Discussion Starter · #1 ·
Hello all ,I have a question about my water system .It is a six stage system with 3 di canisters and is only like 2 months old and everything has been fine till my last bunch of water I made my tds was up like 25 I wouldnt think the filters need changing yet. What the question is how long and often should I flush the filters by that I mean running lots of waste water normally I only let very little waste water out can someone please help I need to do a water change today lol
 

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You should not be restricting the waste output. There should be an inline flow restictor that will set the waste output. If you mean you have a flush kit and are bypassing the restrictor to flush the membrane then that is fine. I would check each of the DI's seperately and see what the results are. Are all 3 DI mixed bed or are they anion deions resins in seperate housings? Just a little odd to have 3 DI cartridges.
 

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spaceman spiff
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A little tricky to follow your train of thought, Mxhonda801. Feel free to use a little more punctuation!

The filters should last longer than just a few months. I normally have to swap my DI resin every 6-9 months, and the membrane will last years (3-5). I'd recommend getting the TDS meter and measuring at the source, immediately after the membrane, and then after each DI as mg recommends (though I agree, it's odd to have 3 on a home system).
 

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My Kitty Cleans My Glass!
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Yeah 3 DI is kinda strange. Correct me if I am wrong, the TDS of the water is going to be from out of the RO Membrane and DI will not affect the TDS? I would make sure to have a flush valve on the RO and if your not running the unit all the time or often, flushing the Membrane will help. I have found that if the unit is not running for a while, the initial output TDS reading is going to be high and will affect your overall water quality.

Mike
 

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Discussion Starter · #7 ·
well you guys kinda answered it.I wasnt running waste water out as I was making water I would just open the valve and run 10 or so gallons out of the waste line now and then .So I assume I need to open the waste line more while Iam making waterI have put in a pic of my system I assume that this thing has 3 DI cartriges on it.
 

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A good rule of thumb is to replace your sediment filter and carbon block after six months. A more precise way to maximize the useable 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. The Matrikx+1 (“Chlorine Guzzler”) for example will remove 99% of chlorine from 20,000 gallons of tap water presented at 1 gpm. 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: <O:p
1. Tap water <O:p
2. After the RO but before the DI <O:p
3. After the DI. <O:p

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?
<O:p</O:p
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 its still approximately 400 ppm.
<O:p</O:p
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 dependant 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.
<O:p</O:p
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 to 3 ppm, 5 ppm, and higher, 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 then would otherwise have been the case. Sometimes the problem is poor quality resin – remember that all resins are not created equal!

Russ
 

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well you guys kinda answered it.I wasnt running waste water out as I was making water I would just open the valve and run 10 or so gallons out of the waste line now and then .So I assume I need to open the waste line more while Iam making waterI have put in a pic of my system I assume that this thing has 3 DI cartriges on it.
The amount of water that comes out of your waste line should be about 4 times the amount of purified water the system produces. The system should have come with a flow restrictor already installed in the waste line that automatically approximates this waste to purified water ratio. Is that not the case?

If you run your system with a ratio too much lower than that, you'll encourage scale build up on the membrane. If you run it with a ratio much higher than that you are needlessly wasting water.

By the way - get yourself a little extra tubing and make sure flow through your DI stages is from the bottom up through each one.

Russ @ BFS
 
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