RO/DI Question

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johnehr

Ignorant and Oblivious
Joined
Sep 18, 2004
Messages
210
Location
Seattle
I bought a 75 gpd RO/DI unit from genghis and its dripping very slowly. Im planning on replacing all the filters, but what are people's opinions on the membrane? I have a feeling its old, but what impact does that have on the rest of the filtration? Is the RO membrane the most likely reason for the slow filtration or are the sediment, carbon, and DI filters?
 
Low water pressure usually causes slow dripping. I bought a pressure pump to go with my RO/DI unit. It runs $70 or so on eBay and puts the pressure up to 80 psi instead of the 40 psi that most houses have. Thats my guess.
 
IMO, replace the filters no matter what, like you plan....including the membrane. That way you are insured a fresh unit. As for dripping slow....there are a number of factors that go into that, as Nashon said, water pressure. Also, water temperature (some units are rated for a particular temp...check the manual for your model), & TDS reading play into it.
 
check your water temperature. that is a big factor here in the seattle. my water comes out of the tap at around 55 degrees. if i boost that up to 70 - 75 degrees my water out easily triples. pressure is also an issue. another thing you can try is to take out the restrictor and re-attach the tubing. let the unit for about 5 minutes or so with full pressure. this will flush the membrane out. after this put the restrictor back in and try again.

i bought a flush kit for mine which does the same thing as removing the restrictor.

if the waste water is coming out at a steady rate then most likely your sediment and carbon filters are not that clogged. they should be replaced though if you don't know how old they are.

an ro membrane should last a long time here....our tds is only 35 coming out of the tap. at least at my house in NE Seattle. if the carbon filter has been changed regularly and kept chlorine away from the membrane then it should still be pretty good. i would flush it like i stated above to get the build up off the membrane.
 
does anyone know how to hook up a automatic shut off for an R/O unit. I got it from natures beverages off the internet and i am not sure how to hook up a shut off. Twice now i have forgotten it was on and over filled my 40 gal. storage tank only to make it rain in the basement. Thank god it is over my mechanical room and no carpet.
 
How do people get warm water to hook up to their RO/DI unit? I just have a water flow valve on my cold water. I dont know if there is anything to get both hot and cold...

Unfortunately I dont have a manual... I think I should have bought one new since I have to replace $100 in hardware when the unit only costs $200 new. Doh!

Can anyone explain how the flush kit works? I see one on marinedepot.com, but they really dont explain anything.
 
My understanding is that using hot water will destroy the ro membrane. If you type in search in auto shut valve ro/di thread you will see the instructions for hook up. I had the same problem till we figured out they company had left out my check valve and then everything worked fine. The flush kit (my understanding) washes the out side of the ro membrane and takes the stuff that it has been keeping out of your water and washes it down the drain thru the waste water line. My units instructions say to do so every month for 4 or 5 minutes. It supposedly will make the membrane last longer and produce good water quanity longer. HTH. Steve
 
I bumped the post I was telling you about so its at the top of the home page. I dont know how to attach it to this one. I am brain defiecnt (even spell check cant help with that mangled word) Steve
 
Steve, I tried that search thing, still unclear. Do I have to buy a seperate shut off unit and/or/also a float for top off water? IF I have a 40 gallon storage tank, how does the ro shut off when it gets full? I landscape for a living, not plumb. Ryan
 
If you go to home at the top of the page you will see a post about rodi shut off valves. where I had problems. You will need a auto shutoff valve a check valve and a float valve. If you just have the float valve it will just drain down the waste line. If you keep with reef keeping you will be ace plumber and electrcian as well. Steve
 
Ryan - see if this thread helps: Anyone Use Kent Float?. I'll look for more information while we wait for responses.

johnehr - we had discussed the water temperature issue at a local club meeting, and I am trying to remember the name of the part/piece that you plumb into the line in order to set the water temperature. I'll do some checking and see if I can't find it. I am needing one for my unit.
 
yeah, hot water will melt your membrane. i think most membranes are rated up to 100 degrees or so but i wouldn't even chance that. the water i run through my membrane is about 78 degrees and that works perfectly. i went from making a gallon in about 45 minutes to an hour down to about 15 minutes. our water in seattle is cold but it's low in tds as well which is good.

the way i did it was to get a mixing valve and hook it up to my sink down in the basement. i turn on the cold water and slowly turn up the hot water till i reach 78 degrees. the tds of the cold water is 35 and the tds of the hot water is 44 so i don't think that will hurt the membrane.

you can also coil a 20+ foot of tubing in a bucket with warm water in it to boost the temperature up.

the flush kit works by bypassing the restrictor in the membrane. at least that is the way my flush kit works. if you don't want to spend the money all you have to do is to remove the product line off the membrane and remove the restrictor. put the line back on and turn on the water for a few minutes. the first time i did this on my membrane and i tested the water and it had a tds of 400. so as you can see the membrane gets build up on it. it took about 8 minutes of running without the restrictor to get my tds of the membrane down to the same tds as the input water.

hope this info helps.
 
Steve,
I looked at my RO unit, it already has a auto shut off valve and a check valve so I don't get how a float valve will do anything. I turned it on and tried to plug the tube the filtered water comes out. The waste water line still had water coming out of it. If by plugging the filtered water line and it doesn't shut off the system, then how does it work. I think I need to see one that is set up to figure this out. But you are right, the more I keep reef, I do believe I will be come a plumber and an electrician. If you have any more input that would be great. thanks Ryan
 
The float valve will close when the holding tank is full. It will build up pressure in the out put line. the check valve will let the pressure keep building untill it shuts off the auto shutoff valve. Thats how I understand it. Steve
 
Matt, I live in Auburn and our water is really cold too. I'm gonna try the mixing valve thing too and see if i can speed up my RO/DI unit.
 
Mine takes 10 min or so to build enough pressure to shut off the output once the float rises. You may just not be waiting long enough.
 
I'm not clear on the mixing valve. What does it look like? Can you provide a link?

Thanks
 
pondguy said:
Steve,
I looked at my RO unit, it already has a auto shut off valve and a check valve so I don't get how a float valve will do anything. I turned it on and tried to plug the tube the filtered water comes out. The waste water line still had water coming out of it. If by plugging the filtered water line and it doesn't shut off the system, then how does it work. I think I need to see one that is set up to figure this out. But you are right, the more I keep reef, I do believe I will be come a plumber and an electrician. If you have any more input that would be great. thanks Ryan

The auto shut off valves sometimes take a few minutes to work - they don't stop the flow instantaneously. I can send you an instructions sheet for an auto shut off valve if you PM me your email address.
 
where is the check valve located, mine is a metal valve screwed into the filtered water out put of the membrane portion, mine goes like this. unfiltered water in and out at the bottom, r.o. membrane out put in and out at the top. I can post a photo if that would help you of the float valve, the waste line, the auto shut off and all parts in the system. Steve
 
I also see great flow improvement by inching my kitchen faucet a little toward the hot in order to get warmer, but still room temperature, water. However, a while back I left for an hour and came back to find my cat had been up there and hit the lever all the way to hot. The whole RO unit was hot. I contacted Kent Marine to see if I needed to replace the membrane. They said the problem would be the glue holding everything together, not the membrane itself. I replaced it anyway. $$$$$
 

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