High TDS on New RO Install... Help

[Tech Savvy]

I installed an RO system about two weeks ago, a 5 stage system from Express Water. Install was pretty easy and it has lowered the TDS of my tap water, but not to the extent it should... I think.

Info:
I'm on well water with a raw TDS of around 900 ppm.
I have a whole house sediment filter, carbon tank filter (Fleck 5600) and a salt based softener (poor quality) in the basement.
The water going into the undersink RO system has a TDS of 830 ppm.
The water coming out of the system has a TDS of 140 ppm.

After I first installed the system using the included filters and membrane, the permeate water (I think that's the correct term) was only 190 ppm. After trying everything I could think of, I bought a new membrane and flow restrictor, assuming the included membrane was junk. I bought a Filmtec BW60-1812 75 and a 550 Flow Restrictor. That brought the TDS down to 140 ppm. But that still seems way too high.

Is there anything else I can try? Could the pre-filters or the post carbon filter also be to blame? Please help if you can.

Thanks in advance.

[vhuang168]

What is the pressure going into the membrane?


Sent from my iPhone using Tapatalk

[Tech Savvy]

Originally Posted by vhuang168

What is the pressure going into the membrane?


Sent from my iPhone using Tapatalk

I don't have a pressure gauge on the RO system, but my pressure tank sticks around 50 - 60 psi. I'm sure the sediment, carbon tank, and softener rob some of the psi. I can bypass all of that for testing purposes and see if that helps. It would just mean that the water going into the RO system would be unfiltered, unsoftened water from the well.

[civics14]

Does pressure affect the amount of sediment removed out of water? I know it makes the RO/DI unit less efficient with more rejection, but didn't think it would affect its capability of doing its job.

Also, that is crazy that your TDS is that high. I thought my tap water was high at 60-70 at the faucet.

[Tech Savvy]

Originally Posted by civics14

Does pressure affect the amount of sediment removed out of water? I know it makes the RO/DI unit less efficient with more rejection, but didn't think it would affect its capability of doing its job.

Also, that is crazy that your TDS is that high. I thought my tap water was high at 60-70 at the faucet.

Yeah, 900 ppm from the well. I've had it tested and it's just very hard water. No pathogens, no sulfer, little iron, normal ph, no nitrate, just very hard. Our softener is also 5 years old and is a whirlpool cabinet unit, not very good. That will be the next replacement with something better.

At 140 ppm coming out of the RO system, the water tastes fine, no different than our home bottle delivery, which is what I'm trying to get rid of. I'm tired of paying $50 to $60 a month in water delivery. I am hoping this RO system would do the job. I think 140 ppm is a huge improvement and it tastes good, I just thought it would be well below 50 ppm.

[Tech Savvy]

NEW DISCOVERY!

As we've been chatting, I was running another test. I bypassed the 3 pre-stage filters and ran the feed line directly into the membrane. That brought the TDS all the way down to 55 ppm!

So, what's the deal with those pre-filters? Are they also just junk filters? Perhaps stealing too much of the pressure?

If the pre-filters are the culprit, what do you guys recommend for pre-filters? The system came with a 5 micron sediment, and two different style 5 micron carbon filters.

Edit: Do I even need the pre-filters? I doubt I'm getting any sediment as the water is already passing through a whole house sediment filter, a carbon tank filter, and a water softener. The carbon filters are probably for chlorine removal, which I have absolutely none. Plus, I have a 10"x54" Carbon tank filter with a Fleck 5600 backwashing control head (1.5 cu ft of carbon) in the basement. Do I really need two more 10" carbon filters on the RO system?

[Bent]

Originally Posted by Tech Savvy

NEW DISCOVERY!

As we've been chatting, I was running another test. I bypassed the 3 pre-stage filters and ran the feed line directly into the membrane. That brought the TDS all the way down to 55 ppm!

So, what's the deal with those pre-filters? Are they also just junk filters? Perhaps stealing too much of the pressure?

If the pre-filters are the culprit, what do you guys recommend for pre-filters? The system came with a 5 micron sediment, and two different style 5 micron carbon filters.

You need to put a pressure gauge right after the last preflter. I bet your water pressure isn't high enough. It needs to be around 50 or higher before the membrane for it to be effective and the pre filters IME will lower the pressure of the incoming by about 10psi or more depending on the size of the filters.



A booster pump would solve your problems. Your also going to need to flush the membrane pretty often with that amount of TDS in the tap.

My advice would be to install an auto flush valve and a booster. That will solve the problem. Also at 98% rejection rate, your TDS coming out of the membrane should be ~17 coming out of the membrane. Any higher than 20 and I would think something is wrong.

But right now I'm thinking the issue is a pressure one.

[Tech Savvy]

Originally Posted by Bent

You need to put a pressure gauge right after the last preflter. I bet your water pressure isn't high enough. It needs to be around 50 or higher before the membrane for it to be effective and the pre filters IME will lower the pressure of the incoming by about 10psi or more depending on the size of the filters.



A booster pump would solve your problems. Your also going to need to flush the membrane pretty often with that amount of TDS in the tap.

My advice would be to install an auto flush valve and a booster. That will solve the problem. Also at 98% rejection rate, your TDS coming out of the membrane should be ~17 coming out of the membrane. Any higher than 20 and I would think something is wrong.

But right now I'm thinking the issue is a pressure one.

Could you link me to a hopefully inexpensive pump?
I've seen manual flush setups by putting a bypass around the flow restrictor. What is an automatic flush valve?


Edit: Would this non-electrical permeate pump do the job? https://www.amazon.com/Aqua-Tec-AQUA...+permeate+pump

[Bent]

Originally Posted by Tech Savvy

Could you link me to a hopefully inexpensive pump?
I've seen manual flush setups by putting a bypass around the flow restrictor. What is an automatic flush valve?


Edit: Would this non-electrical permeate pump do the job? https://www.amazon.com/Aqua-Tec-AQUA...+permeate+pump

Permeate pumps don't do anything but pressurize the vessel for use with a drinking tap. You need a booster.

Before you get it though, you need to install a pressure gauge right before the membrane and see what the pressure is going into the membrane and make sure that is the actual problem. I'm 99% sure it is, but without a number to work with its impossible to say for sure. Here's one:

Malida Water Pressure Gauge Stainless For Aquarium Meter 0-1.6MPa 0-220psi Reverse Osmosis System Pump With 1/4 https://www.amazon.com/dp/B0124FAV6Q..._AU8CxbFRHFNJB

As for the auto flush kit, the manual ones will work by doing what you said, just installing a valve and bypassing the flow restrictor. An auto kit will do it automatically without you having to do it.

Here's some information and how to install it:
https://youtu.be/Qs-qLJE0vRw

Here's the actual piece:
http://www.bulkreefsupply.com/aquate...estrictor.html

Here is the booster kit:
http://www.bulkreefsupply.com/1-4-aq...-pump-kit.html

Be sure to watch the video that is among the pictures in the kit link above, it's also very informative.


But again, before you do anything, check the pressure going into the membrane.

[Tech Savvy]

Thanks for the information. I will pick up a pressure gauge to start with.

[Opus123]

Here is a Plug n play booster that has auto flush. I have never used this unit but it seems to get good reviews and has a $15 rebate right now.

http://www.drsfostersmith.com/produc...0&pcatid=30170

Also, do you know the micron rating on your whole house sediment and carbon filters? Usually you want at least 1 micron with .5 being even better.

[Tech Savvy]

Originally Posted by Opus123

Here is a Plug n play booster that has auto flush. I have never used this unit but it seems to get good reviews and has a $15 rebate right now.

http://www.drsfostersmith.com/produc...0&pcatid=30170

Also, do you know the micron rating on your whole house sediment and carbon filters? Usually you want at least 1 micron with .5 being even better.

Thanks for the link.

The whole house sediment has a 30 micron in it and the carbon tank is usually rated around 15 micron depending on the media that it's filled with. I have 1.5 cu ft of Coconut Carbon in it.

It seems like a 1 micron or .5 micron pre-filter in the RO system would significantly reduce the psi almost guaranteeing that you would need a booster pump? Right now, I have the 5 micron sediment filter in place, but removed both of the 5 micron carbon filters as they are doing what Bent guessed is reducing the psi too much. Leaving those 5 micron carbon filters in place is just about tripling the TDS coming out of the system, so I'm leaving them out for now.

I am doing what Bent suggested and starting with a pressure gauge which should be here in a few days. In the meantime, I am running the system without the carbon filters and only using the 5 micron sediment filter.

1. Are there decent filters that do not drop the psi?
2. Would I be better suited putting a different type of filter in place of the 2 carbon pre-filters considering I have a carbon tank system in the basement and I'm on well water without chlorine anyway? My water tested with zero chlorine and zero chloramines.

[Buckeye Hydro]

Feel free to give us a call when you are in front of the system and we can get it optimized with you - including the carbon tank and softener. The fact that you have a carbon tank on well water tells me you likely have some water quality issues not mentioned above.

Your well pump is controlled by a pressure switch, which typically turn the pump off at 50 psi, and on at 30; or 60/40. So your pressure fluctuates significantly. Additionally you lose pressure as the water passes through the whole house filters as well as the prefilters on your RO system. And no, you likely do not need those carbon prefilters.

With your high feedwater tds, you'll want to pun the system at a higher pressure than most people. A good rule of thumb is to add 1 psi of feedwater pressure for every 100 ppm TDS.

Yes - undoubtedly a booster pump would do wonders in your situation.

Be happy to help further but it gets too complicated for short posts here.

Russ