RO/DI filters

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ronj

Blue Tang
Joined
Nov 28, 2005
Messages
4,490
Location
Destin,Fl
i just changed my first 2 filters on my unit..i forgot to order the other 3rd filter:rolleyes: ..my water pressure was at 40psi before i changed the filters... it's at 57psi now!!!! i still need to get the 3rd filter replaced...my holding tank seems to not putting out as much as it should..i read in the manual that it needs to have pressure put back in it..i lost the manual..i remember something about a bicycle tire pump..is it possible to use one to pressurize it again?????(i expect DonW to chime in soon..he always has knowledge of different stuff):D
 
There is a schrader valve on the yop of the tank. Just hook up your bike pump there. There is a rubber bladder inside that creates the pressure to force the water out.
 
You'll find the reduced water capacity in the tanks will be more related to dirty prefilters. All the water pressure gets backed up there instead of the membrane so you get a much lower production rate and the bladder tank will not fill as normal. Did you replace the carbon or the 1-5 micron white one?
 
i replaced a 5 micron one and one of the carbon filters... the tank capacity is not as much as it was..it used to put out 3g or a little more..now after letting it fill, it will only put out 2 1/2g..i remember reading that when it does this, it needs to be pressurized again
 
mmkeeper may be correct but it's not been my experience. I don't see how the bladder would loose pressure from something like this. If the thrid filter that needs replacing is a carbon block or 1 micron, you still won't have full pressure through the unit.

When you replaced the filters was the membraned flushed and did you allow the prefilters to run by themselves to clean out sediment?
How long does the storage tank take to fill and does the unit shut off properly on it's own??
 
The bladder tank does not normally lose its pressure, its a big heavy rubber balloon and does not go bad easily. You production is probably related to plugged filters causing lower water pressure or water temperature. Those are the two most influential factors in RO production. Replace the third filter and test your water temperature. Do membranes are rated at 77 degrees F and 50 psi pressure, Applied Membranes and GE Water membranes are rated at 77 degrees but at 60 or 65 psi so required greater pressure to produce the same amount of water. Lower temps or pressure have a significant impact on production. You might also check your waster ratio, colder water changes the waste, it goes up quite a bit as the water is denser and does not flow through the membrane as well. It should be about 4:1 waste to good. You can use a clock and a measuring cup to time the flow.
 
it is running much better now..i still have to replace the last carbon filter..i guess i wasn't waiting long enough for the tank to fill
 
Make sure to replace the prefilter and carbons every 6 months like clockwork and to disinfect the filter housings at least once a year during a filter change to keep the unit in good shape.
 
i have to replace my sediment filter much more often than every 6 months..they get nasty really fast here! how do you disinfect the housings??? light bleach???
 
If your prefilter plugs more often it might be wise to use a finer micron rating like a 1.0 or even a 0.5 micron absolute rated prefilter so any sediment is trapped in the prefilter and not passed on the the carbon blocks. That way the carbon blocks will still go the 6 months without plugging. If when you replace the prefilter only you do not see a rise in pressure at the membrane that is evidence that particulates are passing down to the carbons and good carbons are much more expensive than sediment filters. By using good absolute rated prefilters that means they trap everything down to and including their rated micron size. Nominal fliters only trap a percentage of their rated micron size and pass the rest on to the carbons or the membrane shortening the life of both.
Disinfecting the housings is a pretty simple task. I borrowed the following from Buckeye Field Supply:
"We recommend sanitizing your RO/DI system approximately once per year. Schedule this process at a time when you are planning to replace your cartridges. These instructions apply to water purification systems without a pressure tank. Before you begin assure that you have about an hour available, and that your work area and hands are clean.

Turn off the water supply to the system.

Remove all housings and remove all pre-filters and post-filters from the system including sediment filters, carbon filters, in-line filters, and deionization cartridges. Remove the reverse osmosis membrane(s).

Wash housings with a soft brush or cloth in warm soapy water. Rinse thoroughly to remove all soap. Don’t forget to carefully remove and wash all o-rings. Lubricate the o-rings with a small amount of silicone grease and reinstall them.

Fill each vertical housing with one cup of potable water and three to four tablespoons of household bleach, and with this sanitizing liquid still in the housings, screw them back on to the system.

Turn on the water supply a bit, allow water to fill the entire system, and assure water is flowing out of the waste line and the purified water line. Place the outlet of the drain tube and purified water tube slightly higher than the system to assure these tubes are full of the sanitizing solution. When the sanitizing solution has reached the outlet of each tube, and with the outlet of each tube placed above the rest of the system, shut off the water supply for 30 minutes.

After 30 minutes, turn the water supply on and assure that water exits the system from both the drain tube and the purified water port. Flush the sanitizing solution from the system for 5 to 10 minutes.

Turn off the water supply and install new filters.

We recommend keeping a maintenance record for your system. Record the date of the sanitizing and filter replacement."
 
If you have the means to do so. You can simply pump a mixture of hydrogen peroxide and rodi water through the entire system including the membrane. No filter removal or tear down is needed. Let the system run for a hour or so after being flushed with hydrogen peroxide.

Don
 
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