Best RO membrane practice?

[salty joe]

Is it better to run infrequent large or frequent small batches through a RO membrane?

Is it hard on the membrane to sit idle for 6 weeks at a time?

 

[Brad Miller]

Short or long doesn’t matter
If left to sit for that long, bacteria will grow in the membranes, especially if unit is in any sunlight

 

[Buckeye Hydro]

Is it better to run infrequent large or frequent small batches through a RO membrane?

Is it hard on the membrane to sit idle for 6 weeks at a time?[/QUOTE]

A couple of things to keep in mind:

• Any RO system should be run at least once a week.
• When an RO system first kicks on, you'll get a pulse of not-so-clean water coming out of the system, due to "TDS Creep." The effect of that higher TDS water can be minimized by having the system kick on less often, and by having it stay on for a longer period of time each time it turns on. This is one of the important reasons why its not good to have your system controlled by a float valve in your sump.

Russ

 

[salty joe]

Thanks Russ.
I have a dual TDS meter and run the RO water down the drain until TDS is low enough, then I send it to the DI. I've been making large batches of water, then letting things set for 6 weeks or so.
What's the damage caused by long idle times?
I have a needle valve on the waste line to adjust RO/waste ratio due to temperature swings. Would opening that valve up every week to flush the membrane be a good idea?

 

[Buckeye Hydro]

Membrane manufacturers will tell you that a membrane idle for more than a week should be removed and stored in a preservative - due to microbial issues. I'd mod your practice to run it at least once a week. Run it in full production mode - not flush mode.

Russ