RODI Pressure help!

[Kyleqb]

`Hi Guys,

 

I have purchased a 4 Stage RO Super DI Unit 400LPD W/ Dual Pressure gauge.

http://thereefshop.com.au/index.php?main_page=product_info&cPath=11&products_id=535

 

my question is, I have set this up and is running well.

 

at my place the way I have it set up I can select any water pressure I want to hit the RODI.

 

it says if it drops below 50PSI to change cartridges. the thing is I can run it at 150 PSI if I want.

 

would it be better to run it around 75PSI or lower?

I know membranes like high pressure. or should I run it at 100PSI?

 

I'm at a loss when it comes to pressure.,

 

 

thanks

kyleqb

 

[NorthGaHillbilly]

Are you using a booster pump, if not your at the mercy of your house's pressure regulator.

[Kyleqb]

Are you using a booster pump, if not your at the mercy of your house's pressure regulator.

 

No im not using one,

but my house has very high pressure and always has which is a plus

 

I control the RODI with a valve

[NorthGaHillbilly]

 

No im not using one,

but my house has very high pressure and always has which is a plus

 

I control the RODI with a valve

If your house is running over 80 PSI you really need to look into replacing your house's pressure regulator, your playing with fire if its running really high.

[CronicReefer]

You should run it at the recommended flow rate for your membrane. On that website the two membranes they sell for 400lpd flow rates are a Filmtec rated at 50psi and a no-name rated at 100psi.

[Kyleqb]

You should run it at the recommended flow rate for your membrane. On that website the two membranes they sell for 400lpd flow rates are a Filmtec rated at 50psi and a no-name rated at 100psi.

 

Dow Filmtec RO Membrane 400LPD is the one I have.

apparently these are the recommended membranes world wide even on BRS.

it does say 50PSI so I should not go over this

[AZDesertRat]

RO membranes give you higher GPD and better removal efficiencies at higher pressures. Dow membranes are rated for 150 psi working pressure but the weak link is the housings and fittings. If the components are not high quality ANSI/NSF and Uniform Plumbing Code rated for 125 psi working pressure then I would limit the pressure to around 80 psi max. If they are quality components then I would step it up to 100 psi which is where I run my system personally.

 

50 or 60 psi and 77 degrees F are just numbers the membrane industry picked out as a standard to test one manufacturers membranes against anothers for comparions. It is not where a membrane is most efficent or produces the most or best water. Also vendors say 60 psi or whatever for liability purposes so they don't get sued if something bursts or breaks. Again look at the seals and stamps on the housings, lids and fittings to see what you have and go from there. Reputable vendors sell only quality products as their reputation depends on it. Ebay type vendors on the othe rhand are in it for a quick buck and don't rely on repeat customers as they will probably be gone i na few years and selling something else so quality isn't as much a concern. Many don't have a brick and mortar storefront or list and address or phone number for that very reason.

[Kyleqb]

RO membranes give you higher GPD and better removal efficiencies at higher pressures. Dow membranes are rated for 150 psi working pressure but the weak link is the housings and fittings. If the components are not high quality ANSI/NSF and Uniform Plumbing Code rated for 125 psi working pressure then I would limit the pressure to around 80 psi max. If they are quality components then I would step it up to 100 psi which is where I run my system personally.

 

50 or 60 psi and 77 degrees F are just numbers the membrane industry picked out as a standard to test one manufacturers membranes against anothers for comparions. It is not where a membrane is most efficent or produces the most or best water. Also vendors say 60 psi or whatever for liability purposes so they don't get sued if something bursts or breaks. Again look at the seals and stamps on the housings, lids and fittings to see what you have and go from there. Reputable vendors sell only quality products as their reputation depends on it. Ebay type vendors on the othe rhand are in it for a quick buck and don't rely on repeat customers as they will probably be gone i na few years and selling something else so quality isn't as much a concern. Many don't have a brick and mortar storefront or list and address or phone number for that very reason.

 

Thanks champ

So even though it says rated 50psi it will be ok for the membrane to run a bit higher?

 

Thanks for the detailed answer

[AZDesertRat]

Yes, a lot higher. 80 is very good and still safe for most components. Mine has been running at 100 psi for almost 7 years now and getting me 125-140 GPD out of a 75 GPD Dow membrane at 99.4% rejection rate or removal efficiency. DI seems to last forever with that type of efficiency even when my softened tap water TDS is between 550 and 600. Like I said before, the limiting factor is the quality of your canisters and fittings, not the membrane and filters.

[Kyleqb]

Yes, a lot higher. 80 is very good and still safe for most components. Mine has been running at 100 psi for almost 7 years now and getting me 125-140 GPD out of a 75 GPD Dow membrane at 99.4% rejection rate or removal efficiency. DI seems to last forever with that type of efficiency even when my softened tap water TDS is between 550 and 600. Like I said before, the limiting factor is the quality of your canisters and fittings, not the membrane and filters.

Thanks mate. Cool I'll run it at about 80. My housings are good quality

I got a TDS meter yesterday, my tap water runs between 055 - 067 in guessing this is good?

[AZDesertRat]

Very good. The average TDS in the US is about 250 with some areas like Atlanta GA and the Pacific Northwest in the 50's but in the Southwest Deserts where I am at it is between 500 and over 1600.