Hello
I messed up last night. It was 60 degrees here yesterday and I used my pure water system (Hydro Cart) for the afternoon. I came home from work and got distracted before I remembered to bring it inside. I remembered it at 6:30 this morning. I checked the temperature and it was 22 degrees. I brought it inside quickly and now I am nervously waiting for it to thaw out.
After it is thawed, how can I tell if there is any damage? None of the hoses or housings appear (so far) to be damaged. I am concerned about the RO membrane. Is it as simple as hooking it up after it has thawed out this afternoon and checking a TDS reading and looking for leaks?
It’s probably fine. Just run water through it for a few minutes and check the tds. I’ve got one system that is too big to bring in and it’s always fine, but my smaller system I bring in just in case.
I wondered about that. I know that the water lines seemed pretty stiff and they sounded frozen. I was/am hoping that the membrane didn’t have enough time to freeze down deeper. It was below freezing for probably 6 or 7 hours before I brought it inside.
I’m going to check it in a few minutes since it’s now been inside for about 5 hours. I’ll post back later with the results.
If ice or ice crystals did form then damage will take place. Especialy on Cellulose Acetate (CTA) membranes. Most Ro membranes sold today are TFC (Thin Film Composite). They usually will freeze a bit slower than CTA’s, but none the less freezing will damage them as well. Test your TDS to check for damage. If the TDS is over 25 with the same feed water as you usually use, then damage has occured in one or more of the permeate layers. Technically any membrane taken out of service for more than 10 days should be flushed with a preserving soulition for storage not exceeding 6 mos. This is usually not done, so that is another reason RO membranes fail in a couple of years.
Recommended Sterilization/Disinfection Solutions - For Thin Film Membranes
2% Sodium Bisulfite (1 week)
2% Sodium Bisulfite with 20% Glycerine for long term storage (10 days - 6 mos.)
Or you can use - Chlorine Dioxide 500 PPM
Do NOT use Iodine, Quatenary Germicides and Phenolic Compounds
Disinfection Procedure System or Membrane:
Make a water solution containing 2% by weight of sodium bisulfite. Flush and fill the system with this solution. Drain the System as much as possible. Seal the system.
Wet, non used membranes are highly affected by bacteria fouling. especially the Cellulose Acetate ones (paper). It eats the membrane and gradually destroyes them. Daily back flushing the membrane will slow the process if your system is set up or modified to do so.
I should have added that the easiest way to store them for winter is to soak the membrane outside of the cartrage in the sodium solution for 30 mins. Then seal in plastic bag.
Well, it seems that I dodged the bullet here. I used my system all day today and I had TDS readings of 3-5 all day. Hopefully this will make me never repeat this mistake again.
