RO/DI Water Pressure Gauge Placement

[rk4435]

I'm trying to find out the water pressure in my Ro unit to determine if I can add an extra cannister at the end.

The schematics make no sense, I failed Math, repeatedly.

Does the useable water on the unit exit from the DI Resin cannister or the Membrane on top? I can't tell because they are connected.

 

[outdrsyguy1]

it goes through the sediment/carbon filters, then the membrane then last the resin for final polishing. Out of the resin should be 0 tds.

 

[rk4435]

It is 0tds from the resin but it is also over.1 Phosphate. I am considering adding an extra DI stage or GFO stage at the end. It sounds like I should put it on the final water out line to determine the psi there because that would become the in line for the extra stage.

 

[outdrsyguy1]

probably need the pro's to chime in here. I'm wondering if your TDS meter needs calibration, I would think .1 phosphate would be considered a "dissolved solid" and register some TDS. Plus, i'm not sure the test kit works on pure water, i'm always paranoid about testing anything but salt water in the salinity range we work in.

 

[rk4435]

probably need the pro's to chime in here. I'm wondering if your TDS meter needs calibration, I would think .1 phosphate would be considered a "dissolved solid" and register some TDS. Plus, i'm not sure the test kit works on pure water, i'm always paranoid about testing anything but salt water in the salinity range we work in.

That was brought up in another thread about how to lower the PO4 in my RO/DI water and several threads exist on other forums. Apparently it can be measured in fresh. My tank is at .2 PO4 and I have been batteling that for a while. I was shocked to find that my mixing saltwater in a Brute can was registering at .2 as well. I went all the way back to water coming out of the unit and it tested .2. I did not know that RO/DI units needed to be flushed if they have been off. AW&I got me up to speed on that and after a flush the PO4 level dropped to .1 from my RO/DI and my TDS was .004 without the DI Resin canister. They had me do that to determine if my membrane was ok.

Jenn advised that I check the PO4 from the tap, it was 1.0 there. It all seems baffling to me because even with the use of GFO and Rowaphos I've not been able to control it. That's because everytime I have been doing my weekly water change I've been adding a fresh dose of Phosphate and making it impossible for my GFO to catch up.

 

[bcavalli]

I was curious if your running a booster pump? I'm not an expert but I do believe that the membrane needs a minimum amount of water pressure entering it, in order to be effective in the removal Of dissolved contaminates. Don't quote me. But, I vaguely remember 35psi being the minimum for my setup. I believe, the higher the pressure the better up to your limitations on fittings. In my case I had to add a booster pump to increase my PSI to 65 going into the membrane. Hope this helps.

 

[rk4435]

Your right Bcavalli, a booster could be necessary. I can't add one due to the point way it's moved frequently. Getting a good psi reading could help understand what the problem is.

 

[jennm]

I asked about this at work yesterday. I work full-time for a major water filter system and parts supply house in Marietta, and my boss is a certified water quality specialist.

He confirmed what I had said in the other thread. Phosphate would be a dissolved solid and as such, should show up as TDS in your product water. So either the TDS meter is faulty (needs calibration) or the test kit is faulty, because 0 TDS should not have phosphate in it.

He also said that almost ALL problems with RO (and RO/DI) stem from low water pressure.

How are you testing with the meter? Is it an in-line meter or are you collecting a sample of product water and testing it with a hand-held meter? That can make a difference.

Jenn

 

[rk4435]

Thanks Jenn. I am using a handheld meter. The in line meter that came with the unit never worker and I eventually threw it out.

I usually check the water in a bucket as I am filling it. Sometimes I use a clean glass rinsed several times with ro/di water to check. It was .01 or .1 before I changed the filters over the summer.

The thing that has been convincing me that it must be from the ro/di water is that the Phos level seems to stay so high in my tank despite using a reactor.

I have determined that the water pressure gauge goes before the membrane but I cannot determine which line that is. I am also going to order a new Phos Test Kit. Mine is only 7-8 months old but I do have trouble determining the colors on the spectrum but it is certain that a higher than acceptable level of Phos is present and I have quiet a bit of algae in my overflow.

 

[jennm]

Well phosphate in the tank can come from a variety of sources, but the RO water is a different story.

Bo (my boss) also mentioned that if the water sits in the tubing and/or if the tubing is old, that might be an issue too.

I'm suspecting the meter may need calibration - how long since you calibrated it? How old is the probe on it? Both of those are factors.

Jenn