What's the proper way to replace ro/di filters

[Dramad1]

Hello everyboooody. .

I just did a search in the water chem section and could not find what I was looking for, need some advice.

So I'm changing my sediment, carbon and di cartridge's after testing my tds which is now showing .09ppm after di. This is my first time changing the cartridges in my unit which is a refurb 90gpd spectrapure unit. It has been 8 months since I started using my own ro/di unit and changing filters.

 

My question is about installing and flushing the sediment and carbon block cartridges seperate from the di and then flushing the di cartridge. I remember having to flush the di separate from the sediment and carbon block when I first set the unit up but can not recall the steps and I have lost the installation instructions which had the instructions on how the flush the cartridges.

If I remember correctly I flushed the sediment and carbon filter for aprox 30mins or 4 gal of ro water and leaving the di cartridge out of the system. Then I installed the di filter and flushed for another 20-30 mins and or 4 more gal of ro/di water.

What are the proper steps when replacing filters?

I will also be testing to see how my ro membrane is holding up before replacing filters. Plan to measure tds from tap, then tds after ro and before di, then calculate my rejection rate. If less than 90% should I replace? One last thing, I see that spectrapure has a new 99% rejection rated membrane and am curious if it will fit in my 90gpd refurbished unit (mpdi), anyone know. I ask because I'm unsure if the models varies from mpdi to cspdi, max cap etc... I did purchase upgraded filters from the 1 micron carbon block to the 0.5 and the new zz .2 sediment filter and the super di filter. Wondering when the time comes to replace the ro membrane if I can upgrade to the new 99% rejection rated membrane.

[AZDesertRat]

If you do a search with my user name and RO filter replacement it should bring up many posts with my method.

 

Yes the 99% membrane wil fit your housing, it is the standard size and configuration but has been subjected to their special treatment process then individually hand tested and guaranteed 99% rejection rate.

 

Before replacing it though, what is your tap water TDS and your RO only TDS? These are how you calculate your rejection rate or removal efficiency and you may not need to replace it. Do that first. The other two very important factors, well three actually are your water pressure, wate rtemperature and your exact measured waste ratio. You need to know all of these as each has an effect on membrane efficiency.

 

And the TDS is not .09, there is no decimal point, it is actually a power ON indicator so the TDS is 9.

[Dramad1]

Okay so no idea what happened. Replied to post and its not showing up

Water pressure is 90 on the rodi unit gauge

Tap tds is 402ppm

Ro tds before di is 19ppm

Water temp is 26.4°c

Waiting on 2 more filters to arrive before switchung them out. I havent ordered a ro membrane yet. Was going to test it when I replaced my filter cartridges but just checked everything now.

[AZDesertRat]

Changing the sediment and carbon block filters does nothing for the TDS, they are there to protect the RO membrane from suspended solids, silt and sediment, and chlorine.

 

What is your measured waste ratio?

 

Your rejection rate is a litte over 95% which is a little low but not bad. How long had the RO been running when you tested it and how did you test it? I keep a squeaky clean clear glass drinkig water glass, washed by hand is very hot water so it does not have any dishwasher soap residue or anti water spotting films on it. I first take a sample of the tap water, insert the handheld TDS meter and let the reading stabilize. Next I triple rinse the glass and meter in RO/DI or distilled water if I suspect my DI is bad then disconnect the line between the RO and DI so I sample directly from the RO membrane after it has been running 5 minutes or more so any TDS creep has passed and draw a glass of RO only. Insert the handheld meter, let it stabilize, write it down and do another triple rinse with RO/DI or distilled. Reconnect the RO to DI line and again let it run a few minutes then do he final RO/DI test and finally triple rinse the meter and glass and put them away clean and capped for next use.

[Dramad1]

I used a clean glass up, rinsed and dried. I removed my di cartridge and let the system run for almost 10 mins then filled the 24oz glass full and tested with my handheld tds meter

Tds reading after di is still 9

 

Edit just rechecked my tap tds and it is actually 403ppm

 

Not sure about my measured waste ratio. When I was producing 0 tds di water, a ruff estimate would be 20g waste to 5g ro/di. Would I have to collect all waste after making 5g rodi water, or can I just make one gal rodi and use a formula to calculate waste. I have nothing to collect 20g of waste atm. I have my waste water line going down my washer drain

[AZDesertRat]

Use a measuring cup and clock or watch and measure first the waste flow for exactly one minute, dump it and do the same for the treated flow. It should be about 4 times as much waste as treated or 4:1.

[Dramad1]

Okay will do now.

[Dramad1]

Okay so for 60sec run

Waste water is: 5 1/8th cups

Treated flow is just over 1 1/4 cups

[Dramad1]

The remaining 2 filter cartridges just arrived

Is there a way you can post a link to the thread replacing them. I did a search with your name and found many threads but after reading a dozen or so, they all are similar to this one but none with actual steps for flushing new filter cartridges. I want to replace all 3 at once. Thanks

[AZDesertRat]

A cup is 8 ounces so you got 41 ounces of waste or brine and 10 ounces of treated so you are right at 4:1 waste ratio.

 

Remove the sediment and carbon block filters and disconnect the 1/4" line leading from the carbon block up to the RO membrane housing at the RO end, pour two capfulls of regular unscented bleach in the sediment canister and screw both empty canisters back on then turn the tap water on and slowly fill the two canisters until it starts to flow out, turn the water off and let it sit for 5 minutes. Turn the tap water back on and flush the chlorinated water out until all smell is gone. Remove the sediment canister, install the new sediment filter ONLY and turn the water on again and flush for a couple minutes to rinse the glues and binders out. Next install the carbon block and again turn the water on to flush the carbon dust and fines out. Reconnect the line to the RO membrane and replace the DI cartridge or resin. Flush one or two bed volumes or about 1-2 quarts of RO/DI to waste or until you see the finsihed TDS drop to 0 and you are ready to make water.

I just did a couple searches using RO filter replacement and RO disinfection and it brought up dozens of posts with the detailed instructions?

[Dramad1]

Thanks for all the help. I will do another search and see what I come up with. Maybe it was not comingbup because I was putting ro/di filter replacement. Hmmm

Never the less thanks for walking me through it and calculating my tds/waste etc. Very much appreciated. You rock!!