Should I Get A Spare Membrane?

[Dreaming Yachtsman]

Here's the situation: boat is on the hard in Puerto Rico while wife and I are in Oregon for hurricane season. We have a Spectra Catalina model RO unit installed in 2004 still with the original membrane. It has 1155 hours on it and made water at 360-400 ppm just prior to pickling for storage in May this year. We expect to go "down island" towards Grenada this next cruising season then work our way to and through the Panama Canal to position ourselves for a South Pacific run.

We are probably running the original membrane on borrowed time and it may need to be replaced within a year or two. Given that, should I take a spare membrane with me when I return to the boat around November of this year, wait until it gets closer to end-of-life then have one shipped to us wherever we are, or plan ahead now to replace it in Panama or perhaps Mexico, depending on what jump off point we use?

The deciding factors here are: How long can replacement membranes be stored before use (i.e. What is their "shelf life"?) and what is the expected remaining life in our current membrane?

[Therapy]

Don't know about expected life. I think it can be variable.

Shelf life is a year or two if I remember what Tellie said.

Suggest a PM to him if he does not notice my "bump" answer.

[chrisjs]

I would certainly take the spare. You can buy a standard Filmtec 24x40 desal membrane on line for not much more than the cost of shipping one to S.America!! The shelf life on the unopened membrane is 2 years - preferably kept in the coolest place on the boat (eg bilge area). Once opened you can stabilize the membrane with 2% sodium metabisulphite solution. You can also buy the dry material on line inexpensively an drepare your solution as needed.

[Tellie]

Two things that go well together, Spectras and FPs.

Therapy is right, membranes have a shelf life of about a year or so if they remain sealed in their original packaging. This is why I don't recommend taking one for a spare. In your case there are a few things to understand that are important. First, the life span of a well taken care of membrane inside a watermaker is on average 5-8 years. Even though there are rare cases where they last longer yours is more likely near it's natural end. Since the distance is great and it can be more costly to ship a membrane down to PR or elsewhere outside the states, I'd suggest to just take one with you with the intention of just changing it out when you get there. Secondly, though chrsjs means well, never, ever, get any other storage solution besides Spectras SC-1 near your Catalina. Sodium meatabisulphite will pickle the membrane but, as you probably already know and for the information of others with a Spectra, SM will destroy the Clark pump. If you are the original owner of this watermaker the Clark pump is warrantied for as long as you own it. SB will void that warranty period. Thirdly, Spectras are a whole different catagory of watermaker. 360-400 ppm is not unusual especially considering the age of the membrane. But PR is in a warmer and higher salinity zone than other parts of the world so I wouldn't be worried about that reading at all and if pressures and flows are proper would say that's a good ppm range. Fourthly, given your intended route to the South Pacific I would certainly not only recommend a membrane change but, if you do not already have one, a spare feed pump head on board as well. Also your 2005 Catalina did not come with a boost pump. All new Catalinas do and for good reason. Spectra has found that a boost pump is making their feed pumps last a lot longer, I'd highly suggest you consider this addition. It's a simple retro fit. If you ever need any help with your Catalina don't hesitate to send me a PM.

[Amapola]

Your membrane is working on borrowed time. I'd replace it. Membranes should be purchased and installed immediately. They have a short shelf life and cannot be stored as spare parts.

[Cheechako]

replace it...

[chrisjs]

According to DOW specifications their Filmtec saltwater membranes are warranted for 3 years if unopened (not 1 year). So, it is OK to just take it along (in the cool preferably) and wait till you need it. Regarding the use of sodium metabisulphite as recommended by DOW, obviously if this is incompatable with your system, that is a problem. I store my used membrane in its pressure vessel isolated from the pump etc. so do not have this problem. By the way, the biggest problem I had when changing membranes was getting the damn thing out of the housing and getting the new one in. It takes a some force - does not just slide in!! Telli may be more familiar with your system, but for my money I would still carry the spare(s) with you. You can buy a standard 2.5 x 40 inch Filmtec desal membrane for about $150 on line -- it is a "no brainer"!!

[Tellie]

A little confusion. I stated that a membrane has a shelf life of a year or so if left in it's original packaging. I stand by that by experience dealing with thousands of watermakers of all makes. Understanding Dows warranty is important as well. Their very limited pro-rated three year warranty is for membranes that have been installed in a properly operating system. Most of their specifications for a properly operating RO system is intended for commercial applications not simple boat based system that for the most part will never see the proper maintenance, handling, and cleaning service a commercial RO plant sees on a daily/weekly/monthly basis. Also their pre-filtration requirements for warranty are for the most part unrealistic on small cruising boats. Dow will also require that all sub systems operating their membranes have frequent, accurate, upated performance records, in a very specific format that have been available to them routinely and reviewed, this just doesn't happen and is obviously unrealistic on a cruising boat. Secondly the vast majority of average cruisers wouldn't even know the terminology used much less what it means, nor do they really need to. I'm really not trying to be a smart ass, but good luck on a warranty from Dow within a few months of purchase. Dow recognizes many inherent problems with membranes sent via Internet sources. Collectively those big bad watermaker companies that are out to rip everyone off with their membrane prices have had thousands of membranes sent to them from DOW in the last year or so that have failed outright. Many which in good conscience were sent to new customers. It was a nightmare for the big companies. But they were all replaced without question. I can state without hesitation if DY buys a membrane from Spectra and it does not work to specs it will be replaced at no cost when installed in PR or where ever he does it. If it fails within the first year it will be replaced at no cost. There's also a darn good chance knowing the guys at Spectra that they will extend that a few extra months if you're nice to them on the phone. One of the reasons I personally like Spectra above the others. Shipping a membrane from an online second dealer outside of the states is not cheap either. Especially if you need to do it twice because it sat around on the shelf for moths in a hot warehouse. Also the sodium metabisulphite is only incompatible if used to pickle the entire Spectra system. But if a Spectra owner is going to buy a membrane shipped in SM then they should purge the system after install and re-store the system with the appropriate chemicals. Really, as I re-read the above I don't want it to come off as a smart ass reply, I really don't mean it that way. I really like to help cruisers out with their systems and all my advice here is free for the taking, some may correctly think it's worth the price, but there is a lot of misinformation out there that gets owners into a pickle, many times when I eventually come out to their boats, a very expensive pickle.

[Dreaming Yachtsman]

Thanks to all for the replies. I'm a bit curious, though, why only 1 vote registered in the poll. Guess I'll be ordering a spare membrane and replacing it when I get the opportunity within a year.

[Therapy]

Originally Posted by Dreaming Yachtsman

Thanks to all for the replies. I'm a bit curious, though, why only 1 vote registered in the poll. Guess I'll be ordering a spare membrane and replacing it when I get the opportunity within a year.

I didn't vote because I didn't know the answer.

[Dreaming Yachtsman]

Originally Posted by Therapy

I didn't vote because I didn't know the answer.

You're excused. Thanks for your original "bump" reply. My original post must have scrolled off the Portal before most members saw it. I KNOW some members have an opinion and will post it on every thread, whether applicable or not. We seem to be setting records regularly for most number of online users. This a slow season for boaters in the tropical storm zone but really, aren't more people on the water in northern lattitudes in this hot sticky summer weather?

[Capt Kangaroo]

The ppm measurement on my 8 year old Spectra Newport 400 has jumped off the chart in the last few months, so I am in the market for a new membrane. It appears all the 2.5 inch X 40 inch membranes are made by either GE or DOW Filmtec and there are several places on the web that sell them. Are there any recommendations for sellers in the USA or South Pacific?

[chrisjs]

The standard for seawater systems is the Dow Filmtec SW30-2540 (2.5 inch x 40 inch).
It lists for $180 at AmericanRO.com. They are very knowledgeable and helpful. Best price I found last time I checked.

[Capt Kangaroo]

Thank you Chrisjs. That is good information. Do you or anyone else know if the 2.5" diameter membrane is what I need for the Spectra Newport 400 or do I need the 4" diameter? Is the Filmtec SW30-2540 the same "40" High Rejection /High Yield Spiral Wound Reverse Osmosis Replacement Membrane - (KIT-MB-40)" sold by Spectra for $665?

[chrisjs]

Hi Kangaroo
Sorry do not know specifics of Spectra and on-line info is not very revealing ( as you probably already know)!! You should be able to tell easily if it is a 2.5inch diameter vs 4inch just by looking at diameter of pressure vessel. As for whether the standard Filmtec works??? These units seem to operate at relatively low pressure, so they may not be standard membranes. Tellie seems to be the Spectra expert - perhaps he works there? I just hope they are not ripping you off with that price for a standard Filmtec with a different label - there are very few original RO membrane manufacturers. You might still try AmericanRO - perhaps they have answered this question previously.