RO Membrane Help

[Myka]

Originally Posted by Madreefer

Oops my bad Mindy. I do have the 100gpd. Brain fart. I did have a restrictor in there before but I don't remember what it was. I believe I removed it. I will definitely be looking in to putting another one on there and thanks for posting that link Mark, that's good info. I'm thinking 50gpd if possible as I have a pretty big reservoir for RO water

You should have a restrictor in there to match whatever the combined flow of the membranes is. My system runs dual 150 gpd membranes so the restrictor is 300 gpd. The flow restrictor is what forces the water to go through the membrane. If you run the system without a restrictor, you will be causing lots of water to bypass the membrane and very little to actually be going through the membrane. Why would you remove the restrictor?

If anything, you can use a restrictor that is less than the combined flow of the membranes, but then you are causing the membrane to flush less than recommended. So say you have a membrane and system that run 1:4 ratio of good RO to waste. If you use a lesser restrictor then you may cause the system to run 1:2 or even 1:1. By preventing the flushing though, you can cause the membrane to prematurely clog up. So it depends which you prefer - membrane longevity or wasting less water.

[mark]

pressure and temperature effect the output from the membrane so if your not at the membranes specs, been reading using a 75gpd restrictor might not be the best match for a 75gpd membrane. Here talks about trimming the restrictor, can also use a variable restrictor for the change in temp with change in seasons to keep at the 4:1 waste ratio.

[Madreefer]

Ok I went and looked and I did not remove the restrictor. There was quite a bit of confusion when I purchased this unit. So I can't quite remember all that went on. It wasn't supposed to be sold as it was a prototype and was supposed to be for in store use only. I'll try to speak with Albert tomoro and see what he recommends. I would prefer the Vertex membrane but I have never seen any for sale until Tyler mentioned it in an earlier post. Thanks for all the suggestions

[mike31154]

It's unlikely that you will find a 'Vertex' membrane. Vertex, Aquasafe, BRS, Buckeye Hydro & most of the other names you see on RODI units are companies/vendors that assemble the systems from standard, generic components. In our case, that means 10 inch cartridge housings for all your prefilters as well as a standard size RO membrane housing. Apart from that, the only difference is what options each vendor provides for what price. Auto flush, pressure gauge, TDS meter etc. Most of these are 'standard' components as well, sourced from other companies that specialize in their manufacture. I recall seeing one vendor/'brand' out there that individually tests each membrane before selling the system, but you pay for that in final price & to be honest, I'm not sure it's worth it. It's still a DOW membrane.

It's kind of like large appliances. In reality there are only a few actual manufacturers out there and companies like Sears, GE, Whirlpool etc. simply have them built with their own logo, a few cosmetic changes to differentiate them from the competition and on to the showroom floor they go. I'd wager the compressor in every refrigerator out there, regardless of brand name, comes from across the pond to the east.

Quite certain the DOW filmtec membrane is pretty much the standard these days & it's what you'll find in most good quality RO systems, Vertex included. Might be another manufacturer, maybe even two, but they're up against a giant with DOW & unlikely they have the R&D department, let alone the manufacturing might at their disposal to provide meaningful competition.

[Madreefer]

Originally Posted by mike31154

It's unlikely that you will find a 'Vertex' membrane. Vertex, Aquasafe, BRS, Buckeye Hydro & most of the other names you see on RODI units are companies/vendors that assemble the systems from standard, generic components. In our case, that means 10 inch cartridge housings for all your prefilters as well as a standard size RO membrane housing. Apart from that, the only difference is what options each vendor provides for what price. Auto flush, pressure gauge, TDS meter etc. Most of these are 'standard' components as well, sourced from other companies that specialize in their manufacture. I recall seeing one vendor/'brand' out there that individually tests each membrane before selling the system, but you pay for that in final price & to be honest, I'm not sure it's worth it. It's still a DOW membrane.

It's kind of like large appliances. In reality there are only a few actual manufacturers out there and companies like Sears, GE, Whirlpool etc. simply have them built with their own logo, a few cosmetic changes to differentiate them from the competition and on to the showroom floor they go. I'd wager the compressor in every refrigerator out there, regardless of brand name, comes from across the pond to the east.

Quite certain the DOW filmtec membrane is pretty much the standard these days & it's what you'll find in most good quality RO systems, Vertex included. Might be another manufacturer, maybe even two, but they're up against a giant with DOW & unlikely they have the R&D department, let alone the manufacturing might at their disposal to provide meaningful competition.

Yea that all makes sense Mike. And i've never seen a vertex membrane. I replace the membrane every year and I go thru the same thing each time. For the life of me I can never remember which membrane to get. As I said before this was a prototype I was sold so no box or instructions etc. The first time I changed this membrane the one I took out was a 50gpd membrane. I seen that someone posted about getting a vertex membrane and that added more confusion. Note to self....never buy prototype equipment or stuff from fly by night stores.

[mark]

should be getting way more than 1 year from a membrane, how are you determining it needs changing? Are you flushing it, is your waste ratio okay?

[mike31154]

Originally Posted by mark

should be getting way more than 1 year from a membrane, how are you determining it needs changing? Are you flushing it, is your waste ratio okay?

+1 on this, my 75 gpd membane is still the original since I first started the system new in April 2009. So that's 5 years & it still gets my TDS down to 0 in the winter & 1 in the summer (source water TDS is around 165). I ordered a new membrane over a year ago & it's still in the original packaging, waiting to be installed. (Shelf life is probably TX'd, anyone need a 75 gpd membrane?)

I'd say that source TDS & how one runs their system can have a large impact on RO membrane life. In my experience, running the RODI system for a minimum production of 6 gallons has paid off. Most of the time after 6 gallons of RO, I make an additional 7-14 gallons of RODI. Manual flush for a few minutes before & after production is important as well IMO. I would never plumb it into a sump for automatic top offs where the system only runs for short bursts of a few minutes or less. Well, maybe on the west coast where the source TDS is below 10, you can pull that off without too much harm done. Otherwise, the product water never reaches the lowest TDS since the membrane will not have a chance to get properly flushed.

Thanks for the link to the SpectraPure maintenance/info sheet Mark. Great info & I've incorporated the RODI production formula into my fish tank Excel spreadsheet. Incoming water temperature around here varies from 8 Celsius during cold months, to 15 Celsius in late summer. I can't even get close to the 25 Celsius used to rate my 75 gpd membrane. I do well for pressure though, at 91 psi before the membrane. Plugging 8C & 91psi into the formula, the expected gpd for me is 65.75 gpd. Not sure I'm going to mess with my restrictor. I believe mine is incorporated into the manual bypass/flush valve & I don't think it's trimmable like the one on the SpectraPure. In any case, it seems I'm getting close enough to the desired 4:1 ratio & obviously my membrane is liking it, 'cause it's still the original.

[Myka]

Originally Posted by mark

should be getting way more than 1 year from a membrane, how are you determining it needs changing? Are you flushing it, is your waste ratio okay?

That's what I was just thinking.

[mike31154]

Originally Posted by Madreefer

I seen that someone posted about getting a vertex membrane and that added more confusion. Note to self....never buy prototype equipment or stuff from fly by night stores.

Nothing wrong with buying a prototype, as long as you're willing to do a little research & sort the issues out, which is generally not a problem with an RODI system. There's a lot of experience on this site and much of the research has been done by someone already. Witness the fact that I've been corrected on my manufacturer's musings by Steve (StirCrazy). I had no idea there was that much competition banging at DOW's door with respect to RO membranes. In this case, I am guilty of not doing sufficient research before presenting my info!

[Madreefer]

Originally Posted by mike31154

Nothing wrong with buying a prototype, as long as you're willing to do a little research & sort the issues out, which is generally not a problem with an RODI system.

That was my big issue when I received this RO unit. I didn't buy a prototype when I purchased this over the phone. I got hosed. It was supposed to be brand new.