RODI help. AHH

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EVReef3

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I bought this aquamaxx rodi unit(used) a year ago and i couldn't get the TDS to 0. Meanwhile, i have been using safeway 6 stage filtered water which has about 12tds. I am sick of buying water which is only adding nutrients in the tank and pulled the unit out again. I went ahead and changed all of the filters, including the membrane. 10 mins after letting it run, the tds was 50. 1 hour after letting it run it dropped to 10 but i let it run over night. This morning, the TDS is at 25 and it wont change.

This is the one i have; on the right.
Aquamaxx - It's What's Inside That Counts ...

My water source is well water.
Out of tap TDS is: 180
The waste line is :220
Water after rodi is : 25

I dont have any flow restriction, should i get one?
 
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Nutramar Foods
The flow restrictor is needed to allow pressure to be applied to the RODI membrane. Without it you are just wasting water. You should be able to get a matched restrictor wherever you got the membrane.
 
I got the membrane from LFS last night but they didnt have a flow restrictor. The membrane is rated for 75gpd. Could i find a restractor at homedepot, lowes, ace hardware stores?
 
Tidal Gardens
The restricter is essentially a valve. The ones you buy as specially tuned for the gpd of your membrane. If you don't have a flow restricter on the unit I imagine most of your water will be exiting the waste drain and not much if any out of the exit from the unit. You probably already have a flow restricter installed so I predict its possibly something else. Are you running any type of DI unit? What's Tds of your tap water going into it?


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I see there is no DI unit. You may need to purchase a DI addon to get down to zero Tds depending on the Tds of your input water.


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You have a DI, it is on the far left.
 
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AS
A flow restrictor does more than make a difference. You can and will damage the membrane without one.


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Deltec
If the TDS out of the waste line is higher than the tap water TDS then you DO have a flow restrictor.

Lets do some basic troubleshooting:

What exacly did you replace? If it was the sediment and carbon block(s), what brand and micron ranges are they?
What membrane brand and model number did you buy?
Did you disinfect the system while you had it apart?
What is your tap water TDS, water temperature and water pressure?
Using a measuring cup what is your exact waste ratio? Measure the volume from the treated water line for exactly one minute, then do the same from the waste line for exactly one minute. What are the exact amounts in milliliters or ounces? What order are they installed in? Does the one cartridge look like it is made up of small BB's or plastic resin beads?

Did you disconnect or change any of the 1/4" plastic lines?

Disconnect the waste line from the RO membrane housing and look in the end to see if it has a small tube similar to a piece of spaghetti with a small flange on one end stuck in it, this would be a capillary tube flow restrictor. These are much preferred and better than the BRS variety and found and upscale, reef quality RO/DI vendors like Spectrapure and Buckeye Field Supply who specialize in RO and RO/DI not other items with RO as a sideline. You really do get what you pay for so stick with a trusted brand and vendor.

You won't damage a RO membrane without a flow restrictor, you just won't get any treated water as it is the head restriction that forces the water through the membrane. Theywill not work without one period.
 
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Thanks for the clarification just quoting what my RO DI instructions says about not using a restrictor.


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ALL RO membranes use a restrictor, its the only way they will work, otherwise all the flow exits the waste line which would then be the path of least resistance. If your vendor said not to use a restrictor you need to find a more knowledgable vendor.
 
Orphek OR3 reef aquarium LED bar
AZDesertRat said:
ALL RO membranes use a restrictor, its the only way they will work, otherwise all the flow exits the waste line which would then be the path of least resistance. If your vendor said not to use a restrictor you need to find a more knowledgable vendor.
Click to expand...
I will get back to you about your earlier post when i get home. Thanks for the info.
I did check for a restrictor this morning and there is one. Its inside the waste tube coming out of the membrane.

The output TDS has been at 19 for the last day.
 
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The restrictor will be in or on the waste line not the tap water feed line, usually a yellow 1/4" tube which comes off the RO membrane housing in the fitting on the end with two lines and closest to the outside edge as seen in the "end view for membrane" box in this diagram.

http://www.spectrapure.com/huds/DWS-DLX.pdf

The flow restrictor can be in the form of a small white fitting about 3-4" long with writing like 750mL on it or can be like a piece of spaghetti inside the waste line. Membranes must have a restrictor of some sort to work at all, it places backpressure on the waste which forces water to osmose or travel through the membrane leaving the salts or contaminants behind which go out the waste line.

You probably will not find one locally, they are a specialized device. You can try a 1/4" ball or needle valve as a temporary replacement and adjust it so the flow from the waste is approximately 4 times the treated flow or 4:1. This would be a temporary solution only and should be replaced by a properly trimmed capillary tube flow restrictor permanently.
 
Yes i found the restrictor inside the waste line coming out of the membrane.

i changed everything in the rodi.
Sediment filter : 1 micron
5 Micron Matrikx carbon block.
New 75gpd rated Osmonics membrane
I have cold water on, so around 60-61 F


My tap water TDS is 180-182.
Waste from RODI is around 220
I am not sure of pressure as i have it hooked up to the faucet.
I did not replace any tube lines. just the filters and membrane.
 
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Measure your waste to treated water ratio using a measuring cup and watch or clock, each line for exactly minute and tell us how many mL or ounces each is. You are opening the cold water faucet up all the way and not adding any hot wate rat all aren't you? Cold water will treat better than warmer water so the treated TDS should be low depending on your pressure at the membrane. A pressure gauge is an important part of owning and operating an RO membrane, you need to know your pressure.

You should have a 0.5 or no larger than 1.0 micron carbon block for best performance and lifespan. A 5 micron carnon will last a maximum of maybe 6000 total gallons or 1,200 treated gallons and 4800 waste gallons ate the recommended 4:1 waste ratio. A 0.5 will last 20,000 total gallons or 4,000 treated gallons and 16,000 waste gallons at 4:1 and a 1.0 micron 12,000 total or 2,400 treated gallons and 9,600 waste gallons. More important than that is it protects the RO membrane from particulates and colloidal materials much better so it lasts longer and works better so costs less to own and operate.
 
I might have found the problem. Obvious problem, which i didnt catch, dont know why. :/
This rodi was originally rated for 100gpd. The old membrane i took out was also rated for 100GPD
Since i put the 75GPD membrane in there, obviously the flow restrictor needs to be changed. I ordered one to match it. Hopefully that takes the 19 -0.
 
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