Ro/Di filters guys, I need your advice

3n1 · 06/01/2007, 05:54 PM

Here is a little background.

Bought a Water general 6 stage 100GPD ( RD-102 ) more than a year ago. When I first hooked it up, I was getting a horrid waste rate ( about 12 to 1 ). People told me I needed a pressure pump. I let the filter system sit for more than a year with water in it. I finaly got the pump and it still seemed to be dribbling the good water out. So I got on ebay and bought a filmtec 100 GPD Ro and a new set of filters ( 5m sed, 5m Carbon and 1m carbon ). set it all up and still got a 11 to 1 waste rate. aaarrrrgggggggggggggggg.
I called the company up that I bought the Filmtec and filters from and spoke to the owner. He seems to think I have an improper RO restrictor. I have no idea. The restrictor came with the system.

Do you guys think the same, I need a proper restrictor for the 100GPD membrane? If so, PO's me to know that the proper one didnt come with the system to start with.

If this is the case, I need one now. Can I just buy a 1/4" T-valve from home depot and adjust it down to about 5-to-1 restriction? Thats the ratio the owner of the filter company told me I should be getting. I told him my water temp was at 63F and I was using an 80psi pressure booster pump, and he seemed to think it should be about 5 to 1.

3n1 · 06/01/2007, 06:01 PM

Oh yea, one more thing. I timed how long it took to produce 1 gal of waste and how much pure water I got in the time.

in 10 mins, 121 oz of bad and 11 oz. of good.
I figured that out to be 12.375 gpd in good water...not gunna work. LOL I did wait for the system to pressure up and let both lines flow a few minutes before I start the timed test.

bertoni · 06/01/2007, 07:38 PM

The DIY restrictor might help. I'd give it a shot, if you've verified the waste ratio at the Dow web site.

AZDesertRat · 06/01/2007, 07:46 PM

A flow restrictor is less than $10 in most cases. If you want to get real precise get a capillary tube type that you trim to fit exactly for your water conditions. Keep your wate ratio at 4:1 and you have sufficient pressure to drive it through the membrane efficiently.
I would return the 100 GPD Dow Filmtec membrane! That is the worst possible choice for a membrane available from anyone anywhere. It is not even a RO membrane but is in fact a nano filter rated at only 90% rejection. The rejection rate is so poor it is not approved by ANSI/NSF for drinking water in the United States. It carries a rating of "Pool and Spa Use" by the NSF. By comparison the 75 GPD Dow Filmtec membrane is a true RO membrane rated at 98% rejection and is the most popular RO membrane available.
The reason this is important is for every 2% you increase your RO membranes efficiency you double the life of your DI resin. So you could expect 3 or 4 times the life or more out of your DI with the 75.
With a temperature of 63 degrees and pressure of 80 you can expect over 95 GPD out of a 75 GPD Dow if you set the waste at 4:1.

dwl · 06/01/2007, 10:06 PM

Hi guys,
Sorry to but in, I do not mean to hijack, but...
AZDesertRat,
How exactly does one go about getting a capillary tube type flow restrictor, and set it up for a 4:1 ratio?
I recently purchased the Dow 75gpd membrane you are refferring to, and a "matching" flow restrictor and "upgraded" my Watts RO drinking water system (I have yet to upgrade my sediment and carbon filters from their high-micron units, but plan to soon), and it appears to reject a LOT more water than the 25GPD (or was it a 12GPD?) membrane that it replaced. Since this reject water goes down the drain through an air gap faucet, it makes quite a bit more noise than the original. Is there a way for me to reduce the waste water, or at least figure out what my ratio is?
Thanks,
David

AZDesertRat · 06/01/2007, 10:46 PM

Disconnect the waste line from the air gap faucet or put a temporary piece of line in its place and time the flow of both the product or good water and the waste stream using a measuring cup and clock or watch.
Yes the air gap faucet will be noisy as you are making water 2 or 3 times faster than before. When I had my Watts Premier unit I had a 75 GPD membrane and a 750 mL flow restrictor which gave me closer to a 6:1 waste ratio. With the capillary tube type you trim the length andinsert it inside the 1/4" waste line. To adjust the flow you trim more off until you get it right.

3n1 · 06/01/2007, 11:13 PM

Cant return the RO, its been opened and used.

I know the flow restrictor is cheap, but dont think I can find one out here in the boonies. I need one within the next few days. Maybe I'll call buckeye Monday and see if the can get one to me in a hurry.

dwl · 06/02/2007, 06:04 PM

AZDesertRat,
Thanks for the info.
Where can I see and purchase the capillary tube type of flow restrictor you are talking about?
Also, when you had your Watts Premier unit with the 75gpd membrane, did you continue to use the air gap for the waste water, or is there another option.
One more question, are the permeate pumps worthwhile to reduce the waste water ratio?
Thanks.

AZDesertRat · 06/03/2007, 10:29 AM

I know Spectrapure and Kent use capillary tube flow restrictors, I am not sure about others.
Yes with my Watts I did still use the air gap faucet, its actually the best way to meet plumbing codes as most others do not.
I have not tried a permeate pump personally.

sanababit · 06/03/2007, 10:52 AM

hello guys, you could get a 1/4" tubing ball or restriction valve and put in on the drain line and adjusted to the ratio you want doing a time filled diferential between waste water and product water, a good ratio for me is 3 to 1, let me see if i can find a link to valve,
http://www.johnguest.com/part_spec.asp?s=STV_S1

good luck

sana

AZDesertRat · 06/03/2007, 12:51 PM

The ball valve is only good if you can mount it in a place where it cannot be bumped. Its to easy to change the flow with a normal ball valve. A better option is a needlle valve with a locking adjustment, some vendors sell these.

06/01/2007, 05:54 PM	#1
3n1 Registered Member Join Date: Mar 2007 Posts: 80	Ro/Di filters guys, I need your advice Here is a little background. Bought a Water general 6 stage 100GPD ( RD-102 ) more than a year ago. When I first hooked it up, I was getting a horrid waste rate ( about 12 to 1 ). People told me I needed a pressure pump. I let the filter system sit for more than a year with water in it. I finaly got the pump and it still seemed to be dribbling the good water out. So I got on ebay and bought a filmtec 100 GPD Ro and a new set of filters ( 5m sed, 5m Carbon and 1m carbon ). set it all up and still got a 11 to 1 waste rate. aaarrrrgggggggggggggggg. I called the company up that I bought the Filmtec and filters from and spoke to the owner. He seems to think I have an improper RO restrictor. I have no idea. The restrictor came with the system. Do you guys think the same, I need a proper restrictor for the 100GPD membrane? If so, PO's me to know that the proper one didnt come with the system to start with. If this is the case, I need one now. Can I just buy a 1/4" T-valve from home depot and adjust it down to about 5-to-1 restriction? Thats the ratio the owner of the filter company told me I should be getting. I told him my water temp was at 63F and I was using an 80psi pressure booster pump, and he seemed to think it should be about 5 to 1.

06/01/2007, 07:38 PM	#3
bertoni RC Mod Join Date: Mar 2002 Location: Mountain View, CA, USA Posts: 88,616	The DIY restrictor might help. I'd give it a shot, if you've verified the waste ratio at the Dow web site. __________________ Jonathan Bertoni

06/03/2007, 10:52 AM	#10
sanababit Registered Member Join Date: Apr 2007 Location: Uranus Posts: 3,094	hello guys, you could get a 1/4" tubing ball or restriction valve and put in on the drain line and adjusted to the ratio you want doing a time filled diferential between waste water and product water, a good ratio for me is 3 to 1, let me see if i can find a link to valve, http://www.johnguest.com/part_spec.asp?s=STV_S1 good luck sana __________________ Senior Member of the "Hardly any Water Changes, Temp Swinging, T5ing, No Qtining, Frag Exchanging for Fish Food Current Tank Info: 90RR inwall, Octopuss Skimmer, 2 MP40 wQD, 1 MP10 WQD, 2 Radions G4 Pro, Apex Doser, Apex Controller, 400w heater, 30 Gal Sump, Biopellets, Carbon, Gfo, Macroalgae

06/01/2007, 06:01 PM	#2
3n1 Registered Member Join Date: Mar 2007 Posts: 80	Oh yea, one more thing. I timed how long it took to produce 1 gal of waste and how much pure water I got in the time. in 10 mins, 121 oz of bad and 11 oz. of good. I figured that out to be 12.375 gpd in good water...not gunna work. LOL I did wait for the system to pressure up and let both lines flow a few minutes before I start the timed test.

06/01/2007, 07:46 PM	#4
AZDesertRat Moved On Join Date: Jan 2002 Location: NW Phoenix Posts: 16,621	A flow restrictor is less than $10 in most cases. If you want to get real precise get a capillary tube type that you trim to fit exactly for your water conditions. Keep your wate ratio at 4:1 and you have sufficient pressure to drive it through the membrane efficiently. I would return the 100 GPD Dow Filmtec membrane! That is the worst possible choice for a membrane available from anyone anywhere. It is not even a RO membrane but is in fact a nano filter rated at only 90% rejection. The rejection rate is so poor it is not approved by ANSI/NSF for drinking water in the United States. It carries a rating of "Pool and Spa Use" by the NSF. By comparison the 75 GPD Dow Filmtec membrane is a true RO membrane rated at 98% rejection and is the most popular RO membrane available. The reason this is important is for every 2% you increase your RO membranes efficiency you double the life of your DI resin. So you could expect 3 or 4 times the life or more out of your DI with the 75. With a temperature of 63 degrees and pressure of 80 you can expect over 95 GPD out of a 75 GPD Dow if you set the waste at 4:1.

06/01/2007, 10:06 PM	#5
dwl Registered Member Join Date: Apr 2007 Location: mission viejo Posts: 524	Hi guys, Sorry to but in, I do not mean to hijack, but... AZDesertRat, How exactly does one go about getting a capillary tube type flow restrictor, and set it up for a 4:1 ratio? I recently purchased the Dow 75gpd membrane you are refferring to, and a "matching" flow restrictor and "upgraded" my Watts RO drinking water system (I have yet to upgrade my sediment and carbon filters from their high-micron units, but plan to soon), and it appears to reject a LOT more water than the 25GPD (or was it a 12GPD?) membrane that it replaced. Since this reject water goes down the drain through an air gap faucet, it makes quite a bit more noise than the original. Is there a way for me to reduce the waste water, or at least figure out what my ratio is? Thanks, David

06/01/2007, 10:46 PM	#6
AZDesertRat Moved On Join Date: Jan 2002 Location: NW Phoenix Posts: 16,621	Disconnect the waste line from the air gap faucet or put a temporary piece of line in its place and time the flow of both the product or good water and the waste stream using a measuring cup and clock or watch. Yes the air gap faucet will be noisy as you are making water 2 or 3 times faster than before. When I had my Watts Premier unit I had a 75 GPD membrane and a 750 mL flow restrictor which gave me closer to a 6:1 waste ratio. With the capillary tube type you trim the length andinsert it inside the 1/4" waste line. To adjust the flow you trim more off until you get it right.

06/01/2007, 11:13 PM	#7
3n1 Registered Member Join Date: Mar 2007 Posts: 80	Cant return the RO, its been opened and used. I know the flow restrictor is cheap, but dont think I can find one out here in the boonies. I need one within the next few days. Maybe I'll call buckeye Monday and see if the can get one to me in a hurry.

06/02/2007, 06:04 PM	#8
dwl Registered Member Join Date: Apr 2007 Location: mission viejo Posts: 524	AZDesertRat, Thanks for the info. Where can I see and purchase the capillary tube type of flow restrictor you are talking about? Also, when you had your Watts Premier unit with the 75gpd membrane, did you continue to use the air gap for the waste water, or is there another option. One more question, are the permeate pumps worthwhile to reduce the waste water ratio? Thanks.

06/03/2007, 10:29 AM	#9
AZDesertRat Moved On Join Date: Jan 2002 Location: NW Phoenix Posts: 16,621	I know Spectrapure and Kent use capillary tube flow restrictors, I am not sure about others. Yes with my Watts I did still use the air gap faucet, its actually the best way to meet plumbing codes as most others do not. I have not tried a permeate pump personally.

06/03/2007, 12:51 PM	#11
AZDesertRat Moved On Join Date: Jan 2002 Location: NW Phoenix Posts: 16,621	The ball valve is only good if you can mount it in a place where it cannot be bumped. Its to easy to change the flow with a normal ball valve. A better option is a needlle valve with a locking adjustment, some vendors sell these.