New RO/DI system acting weird

Hi all,

I bought a faucet-connected portable RO/DI system from Maxwaterflow over ebay (Reverse Osmosis Systems : Reverse Osmosis | Reverse Osmosis Filter Systems Toronto Canada | Water Filters | RO Units Toronto | Online Reverse Osmosis Systems | Water Softeners Water Purifier Filters). I went with them because only they offered a 75GPD, 5-stage system in a portable form factor. (Under the counter ones don't work for me, as I'm renting.)

The system came with generic, noname filters, and an "Asprinn" RO membrane. From some research it seems to be a Taiwanese company.

Anyway... It came assembled, except for the membrane. Put it in, connected it up, and I was surprised how fast the water was coming. After some measurements, it came out at 4-5 GPH, which is more than double the 75 GPD... Also, the ratio of waste water and product water seems to be around 1:1!

Now, I have tried everything. Reseating the membrane, wrapping the spigot end in teflon tape, pushing it as far as it goes, pushing it in just so it's flush with the case opening, etc., but it seems to be the same.

Now they did say the input pressure shouldn't be more than 65PSI, and I have "pretty good" water pressure, but well within what you'd consider "household normal"... Though I've never measured it. If my pressure is higher, could it have damaged the membrane?
I tried closing the tap somewhat, to a level what I'd consider low pressure for a kitchen sink, and the membrane was still going at ~4 GPH, with 1:1 product to waste.

Now I disconnected the membrane output from the postfilters, I don't want to soak those in whatever gets through the membrane without knowing it's right...

I don't have a TDS meter with me, so I cannot check that right now. Still I'd love to hear ideas or thoughts.

 

It should have a flow restrictor to slow the flow of the water so it can be filtered check if you have one

 

Yep I found it, it's a plastic restrictor plugged into the waste water line. I disconnected, and just flushed the membrane with absolutely no restriction, both the waste and product pipes open.

The waste water did seem somewhat more than the product, but that was also practically flowing. Maybe not more than with the restrictor installed, but definitely didn't seem less either!

 

you may need a better flow restrictor

 

Um... I just double-checked... and WITHOUT the flow restrictor, I get something like 1:1.5! A mile from 1:4.
How does this even work? Shouldn't it start out with all waste, zero product with no restrictor, and then adjust the ratio by cutting the restrictor to size?

The flow restrictor should make sure that the membrane is under pressure, and you get RO water out of it. But mine seems to be leaking "product" water with seemingly zero restriction.

My current diagnosis is that the membrane definitely must be borked. Or can a better restrictor get insane 150 GPD 1:1.5 down to nominal 75GPD 1:4?

 

Sounds like a case of a cheap Rodi system

 

Pm azdesertrat he's a pro with these things. He helped me a while ago with filter choices.

 

Thanks for the hint, that's exactly what I did. I hope he'll have time to help out sometime. In the meantime I need to buy a water quality tester and a pressure gauge.

 

What is your water pressure and your water temperature? Highe rpressures are not a problem, name brand membranes are rated at 150 psi, its the housings and fittings that can be the weak point.

Seat the RO membrane all the way down in the housing, a very light coating of food grade silicone grease or vaseline on the gaskets and O-rings helps if it is tight but just a skin coat. If the waste is still too high try removing the flow restrictor completely and install a 1/4" ball valve in the waste line then adjust it so you get 4:1, waste to treated.


Are you using cold water only? Never blend or temper hot and cold as it is the quickest way there is to ruin a membrane.Turn the faucet on cold only and all the way on, do not try to adjust presure or flow with the faucet.

Any RO or RO/DI can be used portable no matter the brand or model. I never ever recommend the cobbled together little horizontal systems as they are not really any smaller since they usually use the same top bracket and RO membrane housing. The yhave the same footprint as a verical its just they may be 4-5" shorter but its hard to keep them from leaking since all the little throw away filters are just strapped or snapped to the membrane rather than beimng screwed down permanent. Then most use more expensive, shorter lifespan and less efficient throw away sediment, carbon(and usually granular not a solid carbon block) and DI filters.

Honestly if it were me I would return it for a refund and take the money and buy a reef quality RO/DI from somewhere like Spectrapure, PurelyH2o or Buckeye Field Supply. Good systems with a hose thread adapter start at about $130 with full size, low micron sedimen tand solid carbon block filters, name brand Dow Filmtec RO membranes and in some cases 20 oz of fresh blended reef specific DI resin in a refillable full size vertical DI canister and cartridge. All come with an inline pressure gauge and some come with a handheld TDS meter and digital thermometer for as little as $169 complete.

 

Hey,

Thanks for your help.

I'm using cold water only. It's not "freezing cold" though, as I'm living on the 20th floor, it's more like "not warm" cold. I'll check the pressure as soon as I get my gauge from Amazon.

Anyway my biggest problem isn't too much waste water, it's far too little, even with no flow restrictor. (Or rather, far too much "product" water. The membrane is 75GPD, and I get closer to 200GPD.)

Daniel