RO Membrane performance appears to decrease prematurely

[Mjl714]

New Dow Filmtec 75gpd membrane initially reduces tds as expected to 3-6 from tap water of approx 150-155. Around the 4 month mark tds goes up to 10-15 (only 90% rejection rate) doesn’t make sense.

Facts:
Tap water temp generally 60-70 degrees
Coralife 50gpd unit upgraded to 75gpd. Recently changed capillary for 75gpd production
RO product water about 50gal per week
Production, waste to product water 3-4 to 1
Pressure approx 65psi
Local water report DuPage County, Illinois, Lake Michigan water source, doesn’t appear to use chloramines, so I use regular carbon filter.

What do you think?

 

[Crabs McJones]

Do you flush your membrane before and after each use?

 

[Mjl714]

Yes. Especially before making h2o, when the tds starts out high, and I don’t want to send high tds through di resin.

 

[Muttley000]

Yes. Especially before making h2o, when the tds starts out high, and I don’t want to send high tds through di resin.

That almost sounds like you may not be flushing the membrane properly but rather that you are correctly letting the first few minutes of RO go to wate to save resin. There should be a valve you can turn to flush theRO membrane to "blow off" build up. thought it was worth making sure.

 

[Mjl714]

Thanks, and yes i have a flush valve (per Buckeye Hydro) as well as an on / off valve to the di resin. Both are used when flushing the membrane.

 

[Muttley000]

Thanks, and yes i have a flush valve (per Buckeye Hydro) as well as an on / off valve to the di resin. Both are used when flushing the membrane.

I also use a buckeye hydro unit. I would give Russ a call, I'm sure he will have a couple ideas. Let us know what you find out!

 

[Mjl714]

That is where (BH) this is likely headed. Always great service.

 

[Buckeye Hydro]

Thanks, and yes i have a flush valve (per Buckeye Hydro) as well as an on / off valve to the di resin. Both are used when flushing the membrane.

I wouldn't open both (the FLUSH VALVE and the DI BYPASS) at the same time. The DI Bypass is most effective when you have full pressure showing on the gauge.

Russ

 

[Buckeye Hydro]

New Dow Filmtec 75gpd membrane initially reduces tds as expected to 3-6 from tap water of approx 150-155. Around the 4 month mark tds goes up to 10-15 (only 90% rejection rate) doesn’t make sense.

Feel free to give us a call when you are in front of the system and we can help you troubleshoot.

Russ

 

[Mjl714]

Russ, thanks and will call.