Ro filters? How long to filters last? Tdi meter?

lucky777

New member
How often do you guys change ro filters? Do you use tdi meter? Are most rated to do so many gallons or does it very depending on water? Also are you using refillable?

I making roughly 60 to 80 gallons every 2 weeks.
 
Sediment and carbon every 6 months. You need to find out from your local water provider if they are using chloramines. You'll need a different carbon block. Basically when your RO is discharging 10 percent of the TDS of your tap its time for a new RO membrane. Yes, you'll need a TDS meter. When the TDS from your DI resin is above zero, like one, its time to change your DI resin.
 
It's different depending on the water quality in your area. I change my sediment every month or 3 depending on my usage or the color change. Carbon blocks I change when My TDS creeps up (it's different for everybody). Run a dual or triple TDS meter on your setup. I run a triple but duals are more commonplace. With a dual, it is installed in between your carbon blocks and RO membrane and another probe after the DI cartridge. The effluent from your DI cartridge should always read 0-1. I change my DI resin once it hits 2 TDS (others are more religious).

Also, the pressure of your supply water can make a difference in your output, TDS and waste water/product water ratio. If your incoming pressure is less than 50ish, I would suggest an RO pressure pump.

I buy all my RO/DI supplies from BRS. I do not use the refillable carbon blocks, only the DI resin cartridge is refillable on my setup.
 
Testing and monitoring.

I change sediment filter when my pressure drops 5% or more.

I change my carbon blocks when It tests positive for total chlorines in the waste water.

Change DI resin when TDS >000.

Change RO membranes when rejection rate is <98%.

Test and monitor, don't guess or waste your money changing filters that don't need changing.


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It's different depending on the water quality in your area. I change my sediment every month or 3 depending on my usage or the color change. Carbon blocks I change when My TDS creeps up (it's different for everybody). Run a dual or triple TDS meter on your setup. I run a triple but duals are more commonplace. With a dual, it is installed in between your carbon blocks and RO membrane and another probe after the DI cartridge. The effluent from your DI cartridge should always read 0-1. I change my DI resin once it hits 2 TDS (others are more religious).

Also, the pressure of your supply water can make a difference in your output, TDS and waste water/product water ratio. If your incoming pressure is less than 50ish, I would suggest an RO pressure pump.

I buy all my RO/DI supplies from BRS. I do not use the refillable carbon blocks, only the DI resin cartridge is refillable on my setup.



Carbon should be changed at first sign of chlorine getting through. TDS really isn't effective.


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From the FAQ's on our website:
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 more of the prefilters (all the filters that touch the water before it reaches the RO membrane) 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 much of the 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. Remember that all the water you process, both waste water and purified water, goes through the carbon block.

Regarding your RO membrane and DI resin, use your total dissolved solids (TDS) meter to measure, record, and track the TDS (expressed in parts per million [ppm]) in three places: 1) tap water, 2) after the RO but before the DI, and 3) after the DI.

The TDS in your tap water will likely range from about 50 ppm to upwards of 1000 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 do very little to remove dissolved solids. So with your tap water at 400 ppm, you can measure the water at the "œin" port on your RO membrane 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 96% (i.e., they reject 96% of the dissolved solids in the feed water). So the purified water coming from your 100 gpd membrane would be about 16 ppm (a 96% reduction). Filmtec 75 gpd (and below) membranes produce purified water (a.k.a. "œpermeate") more slowly, but have a higher rejection rate (96 to 99%). The lifespan of an RO membrane is dependent upon how much water you run through it, and how "œdirty" the water is. Membranes can function well for a year, two years, or more. To test the membrane, measure the TDS in the water coming into 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 purified water more slowly as their function declines.

After the RO membrane, water will flow to your DI housing. DI resin in good condition will reduce the TDS in the RO water down to 0 or 1 ppm. When the DI output starts creeping up from 0 or 1 ppm, your resin needs to be replaced. Sometimes you'll hear people complain that their DI resin didn't last very long. Often the culprit is a malfunctioning RO membrane sending the DI resin high TDS 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.

Additionally, don't forget to sanitize the entire system at least once per year, and wash and lube your housing o-rings with food-grade silicone grease every filter change.

Russ
 
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