membranes - off season storage

[danno]

I'm planning on leaving my membranes in the towers cause I don't have storage canisters and my membranes are a pain to get out of the towers the way they are mounted on the RO.

Glycerin directions say rinse the membranes with the glycerin solution and then pull the permeate plugs at the bottom of the vessels to drain.

So, when you guys are storing in seperate canisters, do you add a glycerin solution to the canisters and let the membranes "soak" in the offf season, or just rinse the membranes with the solution in the RO, pull them out and place them in the canisters moist?

[brookledge]

Not sure if that is a good idea. You definately need to add preservative to prevent bacteria growth. I think the glycerin??? glycol is to prevent freezing
Keith

[Mark]

I left mine in last year and found that they leaked and went dry, this year they come out.

[Brent]

I will remove mine after cycling them through acid and basic washes.

I made simple storage vessels from 4" sewer pipe with threaded caps. I will keep them in the basement in an
SMBS solution (sodium meta bisulfite) and skip the glycering because there will be no risk of freezing.

[danno]

OK - so I just went to check what I had. It is membrane perservative, not glycerin.

So, do you guys soak the membranes in a full canister of this solution all summer or just rinse the membranes in the solution and store them moist?

[802maple]

I do pretty much as Brent said, and yes you can make your own storage containers like he said. Then you don't have to keep your RO room heated either as long as you make sure it is drained.

I put the membrane in the canister, poor a gallon of solution down thru the membrane, close it off and put it in the basement.

The only different thing I do is I always wash the membrane 3 to 4 times with just a regular wash and then I rinse it thoroughly.

[Brent]

Most membrane manufacturers ship the membranes in a plastic bag, presoaked with the SMBS as a preservative. I'll fill my canisters with the solution, cap them and then rinse them in the laundry a couple times in March before I put them in the RO. Run the first load of sap through to waste to clean out the remaining SMBS.

You only need about a tablespoon of SMBS for each cannister. If you buy a pound or two it will last for years.

[Brent]

If you send your membranes back to Leader or whoever for cleaning they will run them through a couple of washes with the basic solution, then cycle them between a wash with caustic and and acid wash. The acid removes the minerals and the caustic removes the bio-film ... they do that until the membranes run to spec, then flush them with SMBS.

You can do all the above at home with about $ 10 worth of chemicals a year.

[802maple]

You only need to do all that though if you allow them to get overly dirty in the season.

[Gary in NH]

If you make membrane storage containers from PVC pipe and fittings glue them up ahead of time and let the glue cure for a few days before putting the membranes in and sealing the vessel so your membranes don't pick up the glue and primer vapors.

[Brent]

You're going to have some mineral build up no matter how often you rinse and wash with caustic. Maybe you don't need to do the acid clean every year, but it will build up. Think about all that sugar sand ... that's all minerals that have been hammered into the membranes through the season.

It's no big deal to do the acid. The most common one sold by maple dealers is dry citric acid. Mix the acid and run the system a bit ... let it soak ... the DOW instructions say for up to a month !!!! Check the pH after 24 hours. If it doesn't move to neutral in 24 hours, you're done. If it shifts, lower the pH by adding a bit more acid and test again in a day.

[danno]

Sounds good. I guess I'll pull the membranes. How do you guys drain your pumps?

[vtmapleman]

Once I complete my annual closing procedure on the RO (wash/rinse/test) and I am satisfied with the results I put the glycol/acid in and run for 10 minutes eventhough the RO is in a heated room. Once a month I start the RO up for 10 minutes to circulate the Glycol/acid to keep the gaskets moist. I have done this over the last six years and have never had a problem.

[vtmapleman]

Correction on my post - it is not acid I put with the glycol but a preservative. I will use the acid in doing a acid wash which should not sit longer than 30 days...sorry for the confusion.

[Brent]

I'm going to run the same glycol/preservative solution through the system and that should take care of the pumps too.

[tuckermtn]

This may be a silly question, but what size pipe do you need to make a storage vessel for both a 4 inch and an 8 inch membrane?

[Brent]

For my 4" membranes I got stantarrd black plastic sewer pipe from Home Depot.

8" may take a little more hunting down.

[wiam]

I made my 4" with 4" pvc. A glue cap on one end and a threaded cleanout on the other.

William

[RO_Guy]

I have done both the home washes with the sodium hydroxide and the muriatic acid and have had the membranes sent back to CDL and have found that CDL does a much better job of cleaning them.

Weather they have the proper equipment to do the cleaning I don't know but their results are better than mine. When my results plateau, they can squeeze more efficiency out of the membranes.

[Brent]

The report I have is that the pros just do repeated alkaline and acid washes until the get them clean. Nothing you or I couldn't do ... except that it takes some time to baby sit the process and lots of good water.

[ennismaple]

The report I have is that the pros just do repeated alkaline and acid washes until the get them clean. Nothing you or I couldn't do ... except that it takes some time to baby sit the process and lots of good water.

Like anything - just because I can doesn't mean I should do it! I'll gladly pay the experts to clean it properly and use the time I save to work in the woods - or go golfing!

[danno]

I think I saw in the Digest this month that H2O was washing 4" membranes for $75 and 8" for $150.

[Brent]

I don't think you can make any money doing them for $ 75.

It sounds like a "free brake inspection" come on.