RO Membrane: SpectraPure Standard vs SpectraPure 99% RO Rejection?

shawnriv

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Reef Management LLC

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Hello All,

I am looking to replace my two RO membranes on my RODI unit. Since I am running two, do I need the 99% RO rejection filter or the standard filter? Below are links for both the filters:

Standard: https://www.saltwateraquarium.com/s...tFuk8L6RodalrJrONtl3ignhznUZh-xxoCN9cQAvD_BwE

99% Rejection: https://www.saltwateraquarium.com/s...ZzmJLUjI2Oa2YPGncit772qFwP7ozYlRoCeTUQAvD_BwE
I've ran both of these and my tds was no different after membrane and neither were the rejection rates claimed and my rep said it was cause my water was too cold read the fine print... personally I'd go with cheaper one
 
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shawnriv

shawnriv

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I've ran both of these and my tds was no different after membrane and neither were the rejection rates claimed and my rep said it was cause my water was too cold read the fine print... personally I'd go with cheaper one
Thanks for the feedback! My hunch was telling me to go with the cheaper option. But next question, is SpecraPure's RO filters better than competitors? For example, the Bulk Reef Supply option (https://www.bulkreefsupply.com/75-gpd-reverse-osmosis-membrane-dow-filmtec.html) is cheaper.
 

MarineandReef Jaron

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Spectrapure is only a 15-minute drive from us and I have seen their entire facility. The membranes are the same membranes but the 99% are tested on-site and only kept if they can confirm that they get 99% rejection. They do get 99% rejection during testing but the conditions are held constant and ideal. The membranes never perform at 99% rejection for me in my systems.

The basic membranes have one membrane in the lot tested and then the rest are sold.

I have seen spectrapure throw out membranes that did not pass the 99% test but the vast majority make it. So chances are your standard membrane should be just as good as the 99% rejection membrane but there is not the same quality control so there is more variability in the results you could get from the standard membrane.
 

SPS2020

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MarineandReef Jaron

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I would also check out the new spectrapure 150 GPD membranes. They do only get a 98% rejection but they can turn a 75/90 GPD system into a 150 GPD system or a Dual Membrane system into a 300 GPD system.

 
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shawnriv

shawnriv

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Your comparing apples to oranges (90gpd vs 75gpd). Up to you how much water you need to produce in a certain time period.
Speed isn't too important to me honestly. I'm more interested in performance. Are all RO membranes relatively the same? Does one brand outperform another brand?
 

SPS2020

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Speed isn't too important to me honestly. I'm more interested in performance. Are all RO membranes relatively the same? Does one brand outperform another brand?

Personally, I have used the standard Spectrapure for years (since '95) and haven't deviated...they work for me so I haven't searched for another source.
 
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shawnriv

shawnriv

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I would also check out the new spectrapure 150 GPD membranes. They do only get a 98% rejection but they can turn a 75/90 GPD system into a 150 GPD system or a Dual Membrane system into a 300 GPD system.

Thanks! In regards to actual performance, are RO membranes relatively the same? I ask because bulk reef supply sells theirs for cheaper: https://www.bulkreefsupply.com/75-gpd-reverse-osmosis-membrane-dow-filmtec.html
 

KStatefan

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I do not think there is much difference in them anymore. DuPont has reworked the membranes in the last few years and made them better.

I have been testing different membranes the lase few years

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1695914003443.png
 

MarineandReef Jaron

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Speed isn't too important to me honestly. I'm more interested in performance. Are all RO membranes relatively the same? Does one brand outperform another brand?
I think the main difference you will see is quality control. I don't believe BRS batch tests their membranes. The Spectrapure basic membranes are batch-tested and the select membranes are individually tested. Your Basic Dow membrane will likely be as good but there is more variability in the results.
 

Reef Management LLC

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Thanks for the feedback! My hunch was telling me to go with the cheaper option. But next question, is SpecraPure's RO filters better than competitors? For example, the Bulk Reef Supply option (https://www.bulkreefsupply.com/75-gpd-reverse-osmosis-membrane-dow-filmtec.html) is cheaper.
I now use the dow 75 they give me the best rejection for my water with booster pump and I'm in no hurry if I go 100 or 150 the rejection gets worse..... I'd rather wait longer for water then change my di stages more
 

Fredinva

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I now use the dow 75 they give me the best rejection for my water with booster pump and I'm in no hurry if I go 100 or 150 the rejection gets worse..... I'd rather wait longer for water then change my di stages more
I totally agree! the 75s have the best rejection rate. Run it two days and youve got 150!!!
 

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Your comparing apples to oranges (90gpd vs 75gpd). Up to you how much water you need to produce in a certain time period.
A "90 gpd" membrane IS a 75 gpd membrane, but you are told to run it 10 psi over the factory spec. Guess what? any Filmtec 75 will produce about 93 gpd if you run it at 10 psi over factory spec and feed it the spec temperature.
 
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