Probably should show my RO a little love

[Diesel Pro]

All I have ever done is just rinse and store my RO. This season I want to do a decent wash and am looking for some pointers. I bought some soap and a digital PH meter, but never could figure out how to get the PH meter to work. Thinking I should maybe just get some PH buffered soap and call it good?

My home built RO is portable on a wheeled dolly. It does not have a tank of any sorts. Thinking I would either use one of my 65 gallon sap tanks part full or maybe a 6 gallon carboy?

Suggestions for a quick and easy wash appreciated.

[madmapler]

I just use ph strips.

[Diesel Pro]

Well I dug out my PH meter. I also ordered the buffering test solutions so I can calibrate it. I have a couple different soaps here. One says for Filmtec and the other is Ultrasil 10.

[NH Maplemaker]

May not be a bad idea to do an acid wash also if you have never done a thing to the membrane or membranes! So you would need to do a rinse, a soap wash, another rinse, then acid wash, then another rinse, another wash followed by one last rinse! After all that you should be back to as good as new. I an assuming you are doing your rinse after every use! If not that is a must!!

[Diesel Pro]

I've been running this unit for 4 seasons now, but only several hundred gallons of sap per season. After each use I rinse from tank to tank filling my leg tanks full to give them a rinse as well. I don't know that performance has really fallen off, but I fear I'm being neglectful. 2 seasons back I started to do a wash, but dud not do very thorough as I chickened out when I had issues setting up my PH meter.

[Diesel Pro]

OK definitely slowing down, and definitely needs a cleaning. I have some Ultrasil 10 and other soaps here, but no acid wash. Recommended chemical for this project? Is this just a citric acid or do we need to go deeper yet?

[bowhunter]

Here's my recommendation. Do a wash with soap and don't worry about an acid wash for now. The soap or caustic wash is used to primarily remove the organic material fouling the membrane. Acids are used to remove the inorganic salts such as calcium carbonate which isn't as big a problem with the intermittent use sap membranes. I would keep the pH at or below 12 and the temperature at or below 95 degree F which is Dow's recommendation for the XLE membrane. If you use lye for the soap you can just make a 0.1 weight % solution in water to get a pH of 12. For a four inch membrane 5 gallons is plenty of wash volume. It's best to clean a 4 inch with 8-10 gpm of flow through the membrane if possible. Also circulate the soap or caustic solution for about 30 minutes and rinse the membrane to remove all of the soap or caustic. You can repeat the washing cycle if you want to make sure it's clean. Always make sure you rinse out all of the soap after each wash as long term exposure to high pH can damage the membranes. To tell if your membrane is fouled test it when it's new or clean at a standard condition such as 70 psi. As an example my 2540 NF3 will do 0.6 gpm of permeate with 0.2 gpm of concentrate at 70 psi when it's clean. I always test the flow at the end of a permeate rinse to see how much higher I have to run the pressure to get the same permeate and concentrate flow. When my pressure gets up to 90 psi after a rinse it's time to wash with soap or caustic.

If you decide you want to do an acid wash you can use citric acid. It's just a much weaker acid than muratic acid or hydrochloric acid.

[Diesel Pro]

I did have trouble with my PH tester again. It wanted to run off the scale at 12+ and I hardly had any soap. It read vinegar in the 3-4 range though. I ended up with 8 tablespoons in my 6 gallon wash tank. The instructions said something like 6 cups to a 26 gallon wash tank so I should have been plenty safe.

Soap wash did not have much effect. I seem to recall being able to achieve .8gpm with sap at 250 psi and closer to 1gpm with permeate. With permeate I maxed .75gpm. This was cold mind you it was 32°f outside.

So I am at a point where I either try again with an acid wash then soap wash etc or send it in to be cleaned, or maybe just chuck it and start over.

One thing I did see is I do have a bit of iron staining in one of the lines. I must have stored it with tap water (well) rather than permeate or did not rinse completely. I now have the machine home so I can recal my meter and start over. I will say that our well water ph seems to be around 8.

[bowhunter]

The temperature of the water or sap makes a huge difference in the ability to flow permeate. If you're testing at 32 deg F even a clean membrane won't flow very well. You do need to wash with soap in warm water. If you followed the instructions on the soap then you should be ok on the pH. The XLE's are not nearly as sensitive as the NF membranes to pH so I think you're ok. If you can wash it in soap in warm water (95 deg F) and rinse and test it on well water at around 50-60 deg F you should see improvement. I would definitely give it an acid wash before I gave up on it.

[mellondome]

You should truly take the wash temperature as Close to the max allowed for them membrane as possible. This will help immensity with cleaning. Same with acid wash . Probably more along the lines of 114 deg.f. each membrane is different. Check manufactures website. They should list a temp for continuous use and a short duration temp the short duration is the wash temp you want to acheive.

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[mellondome]

Acid wash is citric acid. After recirculating it for an hour or so, let it sit in the membrane for at least 24 hours. This will give the acid time to work.

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[Diesel Pro]

I should note that I did have my wash water on my turkey cooker stand and was running it at about 80°f I did not push it, but now that I have the equipment home I can get after it more aggressively.

[Diesel Pro]

Just a follow up. I filled one of my tanks with well water and started to process permeate for rinsing after wash. My flow numbers are back up to normal. I'm thinking that the cold temps were just messing with me. While I had the RO out I swapped the 240 gph procon for a new 265 that I had as a spare. The old pump had developed a leak at the weep hole and it was definitely time. The bearing was pretty crunchy and the coupling was showing pretty serious wear on the motor end It looked more like <> versus [ ] Runs a lot quieter now and I ran at 250 psi without any issues. I had been having issues starting the motor with my 2000 watt generator. Not sure if this will be cured or not. I'll have to bring the generator home and test before I put it away.