RO/DI Installation Question
 

I purchased a Marine Depot KleanWater Advanced 4-stage RO/DI system, and for $80 added on the drinking water system (a 3-gal tank and sink-installed faucet. And my problem is that I cannot get the waste water line to stop when the system stops calling for RO or DI water.

I emailed the Marine Depot customer service folks and received a link to a video that shows how to install the auto shutoff component. I faithfully followed the video (happy to forward the link upon request) and got a mixed bag of results. At first, it started to work okay, the waste water line opened up when I was making RO or DI water, and then after a slight delay it stopped - good, as it should.

Then I attempted to run DI water again, and the third or fourth time the waste water line again would not stop. I shutoff the water supply and restarted the process, but this time waste water barely trickled out, and again never shutoff until I turned off the water supply.

No flow restrictors came with my system, unless they're built in. I received two skimpy, smallish inline check valves. I installed them (one on the line to the drinking water tank and one on the waste line, but they seem worthless and at one point I heard pressure trying to escape them.

So I have several questions about things I think could be contributors to my problem, but would rather ask the many seasoned, experienced veteran aquarists on this forum, has anyone had this same type of problem? How did you resolve it?

I'm getting solid results on the RO and DI water production. TDS is in the mid to high 200's on the water supply and DI output is zero. But, I'd love to be able to get this system to function the way it is intended without wasting a bunch of water. Thanks in advance for any help.

the waste water will keep flowing as long as there is filtered water output. (I assume you made sure the 3 gal tank is already full when you check for waste water output).
If you completely shut off the RO output (to DI and to your 3 gal tank), the waste water must stop flowing. If it is still flowing, there may not be enough water pressure on input to the autoshut off valve.

I used to have this problem and figured the carbon + sediment filters were reducing the input water pressure too much, so I now only connect 1 carbon + 1 sediment filter. This is ok for me since my input TDS is already quite low.

do a google search (and youtube) to understand the principle, and once you understand how the flow works, it will make more sense when you are troubleshooting to narrow down the cause of the problem.

BTW, there must be a flow restrictor on waste water output of RO membrane, that is how the auto shutoff valve will get the pressure difference to shut off the input.

http://data.reefaquarium.com/wp-cont...5stagerodi.png

when blue line to DI and tank stops flowing, it must build up pressure so the auto shutoff valve will shut off the black (input) line. If there is no pressure build up, it will not shut off input.

you can see if there is leak in red (waste output), then there may not be enough pressure to enable to auto shutoff to shut off the black line. That is the function of the flow restrictor.

If your carbon/sediment filters starts to clog up and reduce input water pressure, it can also make your waste water to continue flowing.

Just a minor nitpick the faucet should be after the storage tank you don't generally drink DI water. You'll need a different shutoff for that path like a float valve on a non-pressure vessel for your top-off water.


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Do you have a pressure gauge on the input so you can see whats going into the system? The most common cause of a drippy waste line is low pressure on the input. Enough pressure has to be on the input to actuate the auto shutoff valve.

Thank you @d0ughb0y. No flow restrictors were included in my system contents. I'm thinking that may be my problem. I just ordered flow restrictors matched to the output of my RO membrane. I will try the setup you suggested when my order arrives I really appreciate your guidance.

Robert

Thanks for your reply @pbaldwin. I do have a pressure gauge. But its accuracy seems suspect. I plan to pickup a separate gauge to check that possible cause tomorrow. My faucet and tank are t'd off prior to DI.and I do have a shutoff for the DI water output line. Do I need a check valve on the line to the carbon filter / tank / faucet for drinking water?

Thanks again for your help. Reef Central is a great resource for newbie reefers like me to get guidance from the vets like you and d0ghb0y. I really appreciate you both taking the time to help me.

Robert

Hi Robert,

We apologize for the trouble with the installation of the drinking water kit.

The capillary flow restrictor should already be pre-installed in the waste water line. Without the flow restrictor, you will not get any product water. Since you are getting product water, the flow restrictor should be there and there should be no need to purchase another.

The two check valves should be installed according to the diagram below. Please take note of the orientation of the check valves as well. Neither of the check valves should be on your waste water line. A check valve installed on the waste water line would mean that one of the lines is missing a check valve and may be the reason why the waste water is not shutting off.

http://www.f3images.com/IMD/aquarium..._Water_Kit.jpg

Please reference your installation with the diagram and let us know how it works out and if we can provide further assistance.

Also, let us know what you find out with the pressure gauge and water pressure as a water pressure below 45PSI may also cause problems.