beetlenut33
Premium member
Yes, that is it. You have a 75 GPD flow restrictor. That means you should be using a 75 GPD RO membrane. Is that what you have installed?not sure is this it?
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Yes, that is it. You have a 75 GPD flow restrictor. That means you should be using a 75 GPD RO membrane. Is that what you have installed?not sure is this it?
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The membrane should last 3 to 5 years. My membrane is 8 years old. The flow restrictor you have is for a 75 GPD membrane, so I would buy a 75 GPD membrane. Try changing it out and seeing if that solves the issue.never replaced the membranes goin on a year and the prefilters are all new . The 550 flow restrictor should be enough right?
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The high TDS that comes out of an RO membrane when you first kick the system on is caused by "TDS creep." In the small residential-scale systems typically used in this hobby, it only takes a minute of two for the RO water ("permeate") TDS to come down to where you'd expect it. For example, here some data from two test runs on a 75 gpd membrane:You have to let it run a while to let the reading stabilize. Is 14 TDS the lowest it reached? Wait like 15 mins.
Assuming you have factory spec water pressure and temperature, your flow restrictor is actually for a 50 gpd membrane. If you have lower or higher pressure or water temperature, you can see how many gallons per gay your membrane should produce using our calculator (link on home page). If the result is somewhere close to 50 gpd, then that 550 flow restrictor should work.Yes, that is it. You have a 75 GPD flow restrictor. That means you should be using a 75 GPD RO membrane.
Remember that RO membranes remove a certain PERCENTAGE of the TDS in the feedwater - so without knowing what the TDS of the feedwater is we can't really say much about the condition of the membrane. In an RODI system we'd ideally like the TDS of the RO water to be less than 2% of the TDS of the feedwater. That would mean a rejection rate of greater than 98%.20-21 TDS is the reason you are burning through your DI resin so quickly. My RO/DI filter is 4 TDS input to the DI resin, and 0 TDS output from the DI resin. My DI resin lasts well over a year.