RO/DI Water

[TXMike]

Not sure if this is the appropriate room, but a question. I have had my RO/DI unit sitting in the closet for a few months. (I know, negligent.) But I want to dust it off and use it for water changes again. My manual says that I need to store the membrane in the fridge, but I didn't. How do I know if my RO/DI water is still good? Standard checks, or something else?

[Spuds725]

It might be ok-- depends if the membrane dried out.

Remove the DI cartridge, Hook it back up, let it run a while and then test the raw water and RO out with a TDS meter.... see what your reduction rate is--- most units fall between 90% to 98%. If you are in that range, the membrane is probably ok. Re-install the DI cartridge and then check the DI out-- it should read 0 (it might be a little high initially, flush it for a while first (5-10 gallons is probably enough).

[Randy Holmes-Farley]

I agree. TDS and flow rate will tell you if it will still work or not.

This article has more:

Reverse Osmosis/Deionization Systems to Purify Tap Water for Reef Aquaria
http://reefkeeping.com/issues/2005-05/rhf/index.htm

[BuckeyeFS]

As you set the system back up, crack open each housing, including the RO membrane housing, and see if you notice any foul oders. The potential for biofouling is a real issue in a system that has been idle for that long.

Russ

[TXMike]

And if I do smell odor?

[BuckeyeFS]

The odor indicates biofouling, and your system should be sanitized:

We recommend sanitizing your RO/DI system approximately once per year. Schedule this process at a time when you are planning to replace your cartridges. These instructions apply to water purification systems without a pressure tank. Before you begin assure you have about an hour available, and that your work area and hands are clean.

Turn off the water supply to the system.

Remove all housings and remove all pre-filters and post-filters from the system including sediment filters, carbon filters, in-line filters, and deionization cartridges. Remove the reverse osmosis membrane(s).

Wash housings with a soft brush or cloth in warm soapy water. Rinse thoroughly to remove all soap. Don’t forget to carefully remove and wash all o-rings. Lubricate the o-rings with a small amount of silicone grease and reinstall them.

Fill each vertical housing with one cup of potable water and three to four tablespoons of unscented household bleach, and with this sanitizing liquid still in the housings, screw them back on to the system.

Turn on the water supply a bit, allow water to fill the entire system, and assure water is flowing out of the waste line and the purified water line. Place the outlet of the drain tube and purified water tube slightly higher than the system to assure these tubes are full of the sanitizing solution. When the sanitizing solution has reached the outlet of each tube, and with the outlet of each tube placed above the rest of the system, shut off the water supply for 30 minutes.

After 30 minutes, turn the water supply on and assure that water exits the system from both the drain tube and the purified water port. Flush the sanitizing solution from the system for 10 minutes or until the water exiting the system lacks the strong smell of chlorine.

Turn off the water supply and install new filters.

We recommend keeping a maintenance record for your system. Record the date of the sanitizing and filter replacement.

Russ

[old salty]

Russ,

Thanks for the excellent advice!!