membrane performance degradation - when is it time to get a new one?

[SilverLeaf]

I'm on my third year with homebuilt RO with XLE 4040 membrane.

First two years membrane worked consistently well. The benchmarks I used were:

When running sap thru @ 250PSI I would get between .75-.9 GPM on permeate line
When running permeat thru @ 200PSI (i.e. during my rinse cycle) I would get 1.2 GPM on permeate line


This year, the first time I used it it performed as above. The second time, performance degraded to:

Sap @ 250PSI - only was getting .6-.7 GPM on permeate line
Permeate thru @ 200PSI - permeate line dropped to about 1.1GPM

I thought "Its too early to have a fouled membrane and have to run a soap wash" so I left it and ran it a few more times as-is. Performance stayed at this slightly degraded level.
Then I did mid-year soap wash.
Performance went back up to the previous level at first, but within 100 gallons had gone back down to the degraded level.

Not sure what to make of this - is this a sign that my membrane is going bad? or something else? Any thoughts from those with more R.O. experience??

[Sunday Rock Maple]

Not sure on your membrane but with mine (filmtec mark e8) when the high ph soap doesn't restore it I run a low ph citrus acid wash. The former works for bacterial fouling and the latter for mineral build up. We've had more minerals than normal this year which also is showing up in more frequent changes with the filter press

[Russell Lampron]

You should do a soap wash after every use to get the bacteria out of it. When you do that the performance should stay at your benchmark. If a soap wash doesn't bring the flow rates back it's time to do an acid wash. If the flows rates don't come back after doing the acid wash the membrane needs to be professionally cleaned or replaced.

[bill m]

I do a soap wash every day I run the RO. Just recently I ran out of the soap I have been using and was given a different brand. I seem to be getting better flow rates through the membrane after using this different soap.

[SilverLeaf]

Interesting.

I may have to give the acid wash a try - I was assuming that since the soap wash brought it back to benchmark for a little bit anyway that that had ruled out the possibility of mineral buildup. But maybe not?

And for you guys that soap wash after every use, how long does the soap wash take you? Admittedly my DIY build is a little primitive, but it takes me a good 3-4 hours start to finish to soap wash (including the rinse at the end). Not practical to do every day. Do you have some faster way to do it? Here's my process:

1) Heat water to 100 degrees, add solution to Ph of 11.
2) Do four cycles of circulating for 15 min (with PSI around 50-60) and letting sit for 15 min. <== This takes two hours!
3) Go through a normal rinse cycle.

[SeanD]

I don't always wash every day, but I did do it a lot this year with the heat fouling the sap more than usual. It takes me about 30 minutes depending on how long I recirculate the soap.

I save a lot of time by filling and heating the wash tank while the RO is still going. Then when the RO is done the second pass and I've flushed the sweet from the membrane I can start the wash right away.

1. Close the recirc. valve and open the main valve wide open to get the highest flow rate possible over the membrane.
2. 5-10 min. rinse with cold permeate.
3. Set the lines to recirculate the concentrate and permeate back to the wash tank.
4. Run the hot soapy water through the membrane for 10-20 minutes. I leave the heater on to keep the soap wash as warm as possible without going over 120 deg.
5. Reset the concentrate line to go to waste.
6. Rinse with cold permeate for 10 min.

[Russell Lampron]

My RO pretty much does everything for me. I set the valves in the proper positions and fill my wash tank with about 15 gallons of permeate. I add about 2 oz of RO soap to the wash tank and start the wash cycle. After the machine has run for a half hour or so I check the pH and adjust to pH 11 if needed. I can then leave the machine and do something else. As the wash solution circulates through the machine and back to the wash tank it gets heated. When the wash solution reaches 43*C/109.4*F the RO shuts off. When the wash cycle is done I drain the wash tank and start the permeate rinse. With that I start the machine and walk away. When the permeate tanks are empty the machine shuts off.

[bill m]

Russell, I do the exact same thing with my H2O machine although sometimes I will stop the rinse cycle to save a little permeate for the next day. I have 1600 gallons of permeate storage and will try to save about 400 gallons if I don't think I will have much sap the next day.

[blissville maples]

I'm on my third year with homebuilt RO with XLE 4040 membrane.

First two years membrane worked consistently well. The benchmarks I used were:

When running sap thru @ 250PSI I would get between .75-.9 GPM on permeate line
When running permeat thru @ 200PSI (i.e. during my rinse cycle) I would get 1.2 GPM on permeate line


This year, the first time I used it it performed as above. The second time, performance degraded to:

Sap @ 250PSI - only was getting .6-.7 GPM on permeate line
Permeate thru @ 200PSI - permeate line dropped to about 1.1GPM

I thought "Its too early to have a fouled membrane and have to run a soap wash" so I left it and ran it a few more times as-is. Performance stayed at this slightly degraded level.
Then I did mid-year soap wash.
Performance went back up to the previous level at first, but within 100 gallons had gone back down to the degraded level.

Not sure what to make of this - is this a sign that my membrane is going bad? or something else? Any thoughts from those with more R.O. experience??

Do a back-to-back soap wash with a good rinse at the end. You'd be surprised what this will do. When they clean them professionally they wash them six or seven times an acid soaked them a couple as well

[Russell Lampron]

Russell, I do the exact same thing with my H2O machine although sometimes I will stop the rinse cycle to save a little permeate for the next day. I have 1600 gallons of permeate storage and will try to save about 400 gallons if I don't think I will have much sap the next day.

I have two 275 gallon totes connected together for permeate tanks. When I don't think that I'll have much sap I close the valve on one of them and save 275 gallons. When that is the case I will do a hot permeate wash instead of a soap wash.