RO/DI ratio 0.75:5

afqu · Feb 2, 2020

Upgrading tank size, and need lots of water. Purchased new prefilters, membrane (75 GPD), DI resin, and BRS flush valve (550). Pressure is about 64 with booster pump. If I flush, the exit hose actually flies off the flush valve. I did remove the old capillary flow restrictor. I have checked and rechecked all fittings etc. Okay, so forget flushing. Overnight my RO/DI produced 10+- gallons in about 9 hours. I did check production straight from membrane and compared to going thru the DI there is only a couple ounces difference. I have had this unit for about 12 years, so not new to me. I am at a loss.

Quietman · Feb 2, 2020

The flush valve is in the shut position (90 degree position) for normal operation?

mfinn · Feb 2, 2020

As long as you have a booster pump, I'd dial it up to at least 75psi or even higher.

afqu · Feb 2, 2020

Quietman said:
The flush valve is in the shut position (90 degree position) for normal operation?

Yes, it is perpendicular to the unit, not inline.

afqu · Feb 2, 2020

mfinn said:
As long as you have a booster pump, I'd dial it up to at least 75psi or even higher.

Is this due to the flush valve I installed, since I have never had this issue before? Does it take more pressure to go thru the flush valve?

Quietman · Feb 2, 2020

afqu said:
Yes, it is perpendicular to the unit, not inline.

Too bad...that would've been easy. 65# should be enough to get close to rated with 550 restrictor. Very cold water can impact too as I'm sure you know. But 1 gallon / hr is very low.

mfinn · Feb 2, 2020

afqu said:
Is this due to the flush valve I installed, since I have never had this issue before? Does it take more pressure to go thru the flush valve?

I don't think the flush valve is going to make a noticeable impact ( maybe a tiny amount, but not enough to worry about).
I have read that the ro membrane is more efficient at a higher psi.

afqu · Feb 2, 2020

Quietman said:
Too bad...that would've been easy. 65# should be enough to get close to rated with 550 restrictor. Very cold water can impact too as I'm sure you know. But 1 gallon / hr is very low. Yes, and I even searched for a calculator and fond this. My water temp is 61 going in. https://www.buckeyehydro.com/calculator/
I am at such a loss. Been playing with this for 3 days now.............grrr. Thanks for your thoughts though

Quietman · Feb 2, 2020

Most RO membranes are rated in the 50-60# range but at 75+ degrees to get 95-96% rejection at rated volume. I can easily see a drop of 25-30% percent with colder or lower pressure (which 65# isnt) but not what...60%?

Have you checked pressure out of filters? You said line blew off so assume pressure is fine though. The bypass valve is installed right way round? I'm reaching a bit.

afqu · Feb 2, 2020

Quietman said:
Too bad...that would've been easy. 65# should be enough to get close to rated with 550 restrictor. Very cold water can impact too as I'm sure you know. But 1 gallon / hr is very low.

Yes, and I even searched for a calculator and fond this. My water temp is 61 going in. https://www.buckeyehydro.com/calculator/
I am at such a loss. Been playing with this for 3 days now.............grrr. Thanks for your thoughts though
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Quietman · Feb 2, 2020

Well, I don't have much to add either...I'm thinking more blockage or connection or faulty filter/membrane (that's a big reach - not sure if that's even a thing) than pressure or temp. Perhaps swapping out old membrane if still around. Reseat all the filters. Which you've probably done already.

afqu · Feb 2, 2020

Quietman said:
Most RO membranes are rated in the 50-60# range but at 75+ degrees to get 95-96% rejection at rated volume. I can easily see a drop of 25-30% percent with colder or lower pressure (which 65# isnt) but not what...60%?

Have you checked pressure out of filters? You said line blew off so assume pressure is fine though. The bypass valve is installed right way round? I'm reaching a bit.

My pressure gauge is mounted on my membrane casing. Yes, the valve is the right direction. The first thing I checked. Is there a way I can disconnect each one and just see how much flow thru each, before going to the next canister? I have the 2 prefilters, then membrane, then DI.

Quietman · Feb 2, 2020

Depends on the unit but that's going to be a royal pain. I'd wait for more advice before starting down that road. Maybe reseat all the filters and reinstall membrane and any visual checks you can do with housing off.

mfinn · Feb 2, 2020

afqu said:
My pressure gauge is mounted on my membrane casing. Yes, the valve is the right direction. The first thing I checked. Is there a way I can disconnect each one and just see how much flow thru each, before going to the next canister? I have the 2 prefilters, then membrane, then DI.

I don't think the information from that would be useful.
If the filters are new and the booster pump is in the correct place ( just before the membrane) the pressure is only really needed at the membrane.

Mical · Feb 2, 2020

Gal per hour is low. I run mine at 82PSI and get almost 12 gals in 2 hours. I use (1)GE 1 micron sediment filter, (1) BRS Universal Carbon block filter 1 micron, (2) Dow Chemical 100gph membranes & 2 BRS DI resin canisters. Tap water in = 456 TDS, after membranes 3 TDS & after DI Resin 0TDS.

mfinn · Feb 2, 2020

Mical said:
Gal per hour is low. I run mine at 82PSI and get almost 12 gals in 2 hours. I use (1)GE 1 micron sediment filter, (1) BRS Universal Carbon block filter 1 micron, (2) Dow Chemical 100gph membranes & 2 BRS DI resin canisters. Tap water in = 456 TDS, after membranes 3 TDS & after DI Resin 0TDS.

Wow, 456 going in and 3 coming out. You have that dialed in.

Mical · Feb 2, 2020

Yea, it's been a learning curve for sure. Luckily I have BRS literally in my backyard (nearby) and I can pick their brains if I have/had questions. Since buying this home and paying for water, I try to make the most of it and not blow alot down the drain. We use waste water for laundry, watering plants, washing skimmers (and other non submersible tank parts) and car washing & cleaning projects. My water bill (including stupid "waste water recovery fee") is about $40 mo. My water to waste ratio is dang near 1 to 1.

afqu · Feb 2, 2020

Quietman said:
Well, I don't have much to add either...I'm thinking more blockage or connection or faulty filter/membrane (that's a big reach - not sure if that's even a thing) than pressure or temp. Perhaps swapping out old membrane if still around. Reseat all the filters. Which you've probably done already.

I removed both prefilters and same thing, about 32 oz in 20 minutes. Going to remove membrane........again, but run it without and I should have a lot of water coming thru, right?

Quietman said:
Well, I don't have much to add either...I'm thinking more blockage or connection or faulty filter/membrane (that's a big reach - not sure if that's even a thing) than pressure or temp. Perhaps swapping out old membrane if still around. Reseat all the filters. Which you've probably done already.

It was the brand new membrane. Got another and all is back to normal, better than normal actually.