TDS question

frogger1again · 12/21/2006, 10:28 PM

I have a 6 stage RO/DI. However, I don't have enough pressure to run the thing. So, I bypassed just the membrane and kept the other 5 filters going which give me plenty of water. However, my tap going into the filter is around 120 and after the 5 filters its only down to around 105. Shouldn't I see a much better response than this???
One thing to add....I never really got to do the break in period because it dribbled out about 1 drop every 2 seconds. Can these TDS reading be coming from particles that were never initially flushed out? I have it on and plan on leaving it on for a while to see if TDS lower. Any advice or thoughts would be much appreciated!

Thanks!

Craig Lambert · 12/21/2006, 10:33 PM

TDS should read 0. It shouldn't need to run for very long at all to give you an idea of what's being removed. A tap reading of 120 is bad. I've seen much much higher than that, so your system is not cutting it right now. How old are the filters? It may time to replace them.

AZDesertRat · 12/21/2006, 10:37 PM

Craig you have it all wrong. An RO unit without an RO membrane will not remove TDS so it will never be 0. A tap water TDS of 120 is fantastic, much better than the national average of 250 and certainly better than my 835. It does not matter tha age of his filters, without using the RO it will basically be an expensive taste and odor filter and nothing more. Frogger, I answered your questions on your other thread, no need to cross post your questions will be answered.

Craig Lambert · 12/22/2006, 09:55 AM

My interpretation was that he removed the pre-filter membrane. The first in the line of 6. If it is the RO membrane he bypassed than certainly I agree with you.

miztic · 12/22/2006, 10:13 AM

You'll be better off just buying a booster pump and run the RO/DI unit propperly, I suspect that you'll make up the expense in saved DI cartridge refills in under a year.. running that much TDS through a DI stage will wear it out really quick..

goda · 12/22/2006, 10:18 AM

your looking at getting about 60 gallons before you need to replace the di.. unless you run the membrain..

what is your psi at... any psi can run a ro unit ( at work we have 24 psi and it runs fine... slow but fine.. so we do use a booster pump but somtimes i forget to plug it in)

AZDesertRat · 12/22/2006, 10:28 AM

I don't think he will get anywhere near 60 gallons out of the DI. 16 oz or one pound of resin will treat about 2000 total TDS so if he has a 16 oz cartridge he will see about 19 gallons if its 105 TDS going in. If he has a 24 oz vertical canister type DI he will treat about 3000 total TDS or 28.5 gallons. If he has an e bay 6 oz cartridge forget about it.

12/21/2006, 10:28 PM	#1
frogger1again Registered Member Join Date: Oct 2005 Location: Vancouver, WA Posts: 23	TDS question I have a 6 stage RO/DI. However, I don't have enough pressure to run the thing. So, I bypassed just the membrane and kept the other 5 filters going which give me plenty of water. However, my tap going into the filter is around 120 and after the 5 filters its only down to around 105. Shouldn't I see a much better response than this??? One thing to add....I never really got to do the break in period because it dribbled out about 1 drop every 2 seconds. Can these TDS reading be coming from particles that were never initially flushed out? I have it on and plan on leaving it on for a while to see if TDS lower. Any advice or thoughts would be much appreciated! Thanks!

12/21/2006, 10:33 PM	#2
Craig Lambert Premium Member Join Date: Dec 2002 Location: Portland, OR Posts: 2,897	TDS should read 0. It shouldn't need to run for very long at all to give you an idea of what's being removed. A tap reading of 120 is bad. I've seen much much higher than that, so your system is not cutting it right now. How old are the filters? It may time to replace them. __________________ "Give a man a fish and you feed him for a day. Teach a man to fish and he will spend all day in a boat drinking beer." Current Tank Info: 75G Tank, 29G Sump, 100lbs LR, AquaC EV-180, Iwaki MD-20RT return Tunze nano streams 4X54 t-5/Icecap Ballast & SLR's 2x110 vho actinic

12/22/2006, 09:55 AM	#4
Craig Lambert Premium Member Join Date: Dec 2002 Location: Portland, OR Posts: 2,897	My interpretation was that he removed the pre-filter membrane. The first in the line of 6. If it is the RO membrane he bypassed than certainly I agree with you. __________________ "Give a man a fish and you feed him for a day. Teach a man to fish and he will spend all day in a boat drinking beer." Current Tank Info: 75G Tank, 29G Sump, 100lbs LR, AquaC EV-180, Iwaki MD-20RT return Tunze nano streams 4X54 t-5/Icecap Ballast & SLR's 2x110 vho actinic

12/21/2006, 10:37 PM	#3
AZDesertRat Moved On Join Date: Jan 2002 Location: NW Phoenix Posts: 16,621	Craig you have it all wrong. An RO unit without an RO membrane will not remove TDS so it will never be 0. A tap water TDS of 120 is fantastic, much better than the national average of 250 and certainly better than my 835. It does not matter tha age of his filters, without using the RO it will basically be an expensive taste and odor filter and nothing more. Frogger, I answered your questions on your other thread, no need to cross post your questions will be answered.

12/22/2006, 10:13 AM	#5
miztic Premium Member Join Date: Jan 2005 Location: Glendale Heights, IL Posts: 591	You'll be better off just buying a booster pump and run the RO/DI unit propperly, I suspect that you'll make up the expense in saved DI cartridge refills in under a year.. running that much TDS through a DI stage will wear it out really quick..

12/22/2006, 10:18 AM	#6
goda Moved On Join Date: Mar 2006 Location: fortlauderdale florida area Posts: 1,874	your looking at getting about 60 gallons before you need to replace the di.. unless you run the membrain.. what is your psi at... any psi can run a ro unit ( at work we have 24 psi and it runs fine... slow but fine.. so we do use a booster pump but somtimes i forget to plug it in)

12/22/2006, 10:28 AM	#7
AZDesertRat Moved On Join Date: Jan 2002 Location: NW Phoenix Posts: 16,621	I don't think he will get anywhere near 60 gallons out of the DI. 16 oz or one pound of resin will treat about 2000 total TDS so if he has a 16 oz cartridge he will see about 19 gallons if its 105 TDS going in. If he has a 24 oz vertical canister type DI he will treat about 3000 total TDS or 28.5 gallons. If he has an e bay 6 oz cartridge forget about it.