Added a second RO membrane to my Ro unit last Sept so as to fill my 390 gallon tank quicker, at the same time I changed out the DI resin, carbon blocks and sediment filters. After doing all that I checked my TDS, at first it was reading around 70 TDS but began to drop to a low of 34, I could not get the TDS any lower, if the filter was not used for a couple of days the TDS would be over 100, I have noticed that lately Im starting to get algae on my rockwork, so today I looked at my resin and all three canisters were still blue so Im thinking maybe the water is channeling through the resin, I removed the first canister opened the resin canister all the resin is still blue, so I pour it out and re-pack it. I see the arrow on the canister pointing up and lettering that reads this end up toward cap. Now when I installed these I used only two and I saw that arrow. A week ago I added the third canister hoping my TDS would drop, it did not. So now im thinking to myself you dummy you installed all the canisters upside down, well sure enough I checked the other two and they were both upside down. I went 10 months with this pumping TDS straight in to my tank and storage unit. So those of you that may be having TDS issues with your RO DI units check the orientation of your DI canisters. I am now getting 0 TDS. Hope this helps someone.
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saltyphish
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At least you finally figured it out.
redfishbluefish
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Definitely a "DOH" moment!
This should be a good lesson for you. You should be testing the TDS on a regular basis using a good ATC handheld TDS meter from all points. By this I mean tap water TDS and RO only TDS which are used to calculate the membrane efficiency or rejection rate plus after each DI stage. When you have multiple stages of the same DI resin it is common practice when you start to detect TDS in the first canister or cartridge to move the downstream DI inot the first position and add the new cartridge or refill to the second. I can't imagine needing more than 2 DI cartridges, if you still have problems it means your membrane is not working as it should. My tap TDS varies between 550 and 850 and I get about a year out of my first DI and 3 years out of the second with a 100G reef with a 30G sump and a 16G nano.
When you added the second membrane did you check your pressure and your waste ratio. Dual membranes require a minimum of 65 psi to operate and the flow restrictor for a single membrane is not the same as one for dual membranes if you expect good water quality, membrane life and DI life.
What is your tap TDS, RO only TDS before DI, first DI TDS, second DI TDS and third DI TDS? What is your water pressure at the membrane and your water temperature? What is your exact measured waste ratio? What are you using for membranes and replacement filters? Are you using soft or softened water or hard water?
DI cartridges should be plumbed in a bottom up flow configuation so all resin and water come into contact with each other and they do not channel or short circuit. Never ever rely on color changing resins, in fact color changing actually uses dyes which add TDS. Use non color changing resin and rely on your handheld temperature compensated TDS meter for accuracy.
When you added the second membrane did you check your pressure and your waste ratio. Dual membranes require a minimum of 65 psi to operate and the flow restrictor for a single membrane is not the same as one for dual membranes if you expect good water quality, membrane life and DI life.
What is your tap TDS, RO only TDS before DI, first DI TDS, second DI TDS and third DI TDS? What is your water pressure at the membrane and your water temperature? What is your exact measured waste ratio? What are you using for membranes and replacement filters? Are you using soft or softened water or hard water?
DI cartridges should be plumbed in a bottom up flow configuation so all resin and water come into contact with each other and they do not channel or short circuit. Never ever rely on color changing resins, in fact color changing actually uses dyes which add TDS. Use non color changing resin and rely on your handheld temperature compensated TDS meter for accuracy.
My water pressure is 65. Im using softened water, my tds in is 388. Im doing the low waste ro which means im running the waste water from the first membrane through the second membrane. I have read that you will get a higher tds coming out. I use a dual tds meter, before the first membrane and after the last DI resin canister. With aquariums everything is a lesson. My first aquarium was a 55 gallon and i use to go to the store and buy the 2.5 gallon distilled water for topoff and water changes. That was back in the middle eighties and the corals looked great, that is also when live rock was the new filter. Anyway before i built this aquarium i was using a 100 gallon rubbermaid stocktank to hold my livestock and my tds was zero. Adventures in aquariums right, never a dull day. Thanks for your post and have a great day.
You really need a good handheld TDS meter, the inline lacks the accuracy but more importantly is not giving you enough information. You need to know tap TDS, RO only TDS and the TDS after each DI stage. Without all of those you could be doing more harm than good as an exhausted DI starts passing weakly ionized substances evene before it is fully exhausted and many of these do not register well on a TDS meter so it is very important to catch this quickly.
Dual membranes are not and should never be considered a water saver, if someone told you this they are misinformed. It is even more important to keep the waste ratio at 4:1 since you are passing the concentrated brine from the first membrane into the second so it will die quickly if it is not well flush via the waste line. You need to measure your exact waste ratio and adjust it accordingly with a properly trimmed capillary tube flow restrictor. Both Spectrapure and Buckeye Hydro sell these for $5-$6.
Dual membranes are not and should never be considered a water saver, if someone told you this they are misinformed. It is even more important to keep the waste ratio at 4:1 since you are passing the concentrated brine from the first membrane into the second so it will die quickly if it is not well flush via the waste line. You need to measure your exact waste ratio and adjust it accordingly with a properly trimmed capillary tube flow restrictor. Both Spectrapure and Buckeye Hydro sell these for $5-$6.
mcarroll
10K Club member
In my experience it causes a lot of wear and tear on the pieces to install and uninstall capillary restrictors.
One might have to do this numerous times during tuning - even seasonally out here where the water temperature drops through the floor in the winter.
I've had good luck using alternatives, but do you have any tips to make tuning/trimming these capillary restrictors easier?
One might have to do this numerous times during tuning - even seasonally out here where the water temperature drops through the floor in the winter.
I've had good luck using alternatives, but do you have any tips to make tuning/trimming these capillary restrictors easier?
I keep two capillary tubes, one for summer and one for winter. Changing them out is as simple as releasing the waste line from the speed fitting, pulling the tube out of the line with my fingers or a pair of small hobby pliers and inserting the new one. Never been a problem?
I have tried, and still own a very expensive needle valve but do not like it as the flows drift with time, I ruined a RO membrane in fact using this method when the waste dropped to almost nothing and I didn't catch it in time since it was going to the P trap with a saddle tap at the time.
I have tried, and still own a very expensive needle valve but do not like it as the flows drift with time, I ruined a RO membrane in fact using this method when the waste dropped to almost nothing and I didn't catch it in time since it was going to the P trap with a saddle tap at the time.
mcarroll
10K Club member
I have never been brave enough to mount the waste line where I can't see it. 
Not that I would have anticipated what happened to you....but it seems like most of the (very few) problems people experience with RO systems happen because they couldn't see the waste water (or lack of) and thereby notice there was a problem.
Not mounting it can be a pain in the butt all by itself though. I keep the waste line pinch-clamped to the side of a utility sink, so it's kinda always in the way whether in use or not. Not perfect, but I generally don't miss performance changes like no waste water flowing.
Using the force of pliers was needed on my capillary restrictors too - seems like it should be a smoother operation. I'd be afraid of leaks for a week after changing one out.
I found that removing and replacing it caused heavy wear on the capilary mount (whatever you call the hard plastic piece of the restrictor) which was often stuck inside the fitting, the push-fitting itself as well as the tubing. I had to stop doing it so I could stop worrying and before the fitting was so damaged that it would need to be replaced.
Luckily you mentioned Buckeye Hydro and they also sell these mini-needle valves with a locking collar for $5.
I've been using one of these in place of an ordinary restrictor for the last several winters now with no issues.
It goes on the end of the waste line during cold weather and when the collar is locked, flow does not drift. I can also easily change the flow as needed without using any force at all, which is both nice, and handy: Some days in the winter will give me water cold enough to cause frost bite....other days it's pretty mild so the flow is better and I can take advantage of it.
I take the valve back off in the spring and just rely on a "fast flush ball valve" type restrictor that came with my system and it seems to work well enough when the water is nice and warm. (I haven't had any performance problems with that either, but it's very old and the valve handle is getting a little rickety.)
Not that I would have anticipated what happened to you....but it seems like most of the (very few) problems people experience with RO systems happen because they couldn't see the waste water (or lack of) and thereby notice there was a problem.
Not mounting it can be a pain in the butt all by itself though. I keep the waste line pinch-clamped to the side of a utility sink, so it's kinda always in the way whether in use or not. Not perfect, but I generally don't miss performance changes like no waste water flowing.
Using the force of pliers was needed on my capillary restrictors too - seems like it should be a smoother operation. I'd be afraid of leaks for a week after changing one out.
I found that removing and replacing it caused heavy wear on the capilary mount (whatever you call the hard plastic piece of the restrictor) which was often stuck inside the fitting, the push-fitting itself as well as the tubing. I had to stop doing it so I could stop worrying and before the fitting was so damaged that it would need to be replaced.
Luckily you mentioned Buckeye Hydro and they also sell these mini-needle valves with a locking collar for $5.
I've been using one of these in place of an ordinary restrictor for the last several winters now with no issues.
It goes on the end of the waste line during cold weather and when the collar is locked, flow does not drift. I can also easily change the flow as needed without using any force at all, which is both nice, and handy: Some days in the winter will give me water cold enough to cause frost bite....other days it's pretty mild so the flow is better and I can take advantage of it.
I take the valve back off in the spring and just rely on a "fast flush ball valve" type restrictor that came with my system and it seems to work well enough when the water is nice and warm. (I haven't had any performance problems with that either, but it's very old and the valve handle is getting a little rickety.)
My old RO/Di started out life as a drinking water system so was plumbed under the kitchen sink where I could not see the waste. Since that time I added both a water softener and a laundry sink and mounted the RO/DI on the wall above the sink so it is easier to operate and maintain. The waste line extends over the lip of the sink and is fastened down with a small nylon clamp like used to secure coaxial cable to the side of the house. In this way I have an air gap to meet plumbing codes as well as it is visible and easy to measure the waste ratio every so often.
The needle valve I have is exactly the one you pictured but it still drifts with time so I find the capillary tube much safer. The needle and seat start to scale up even with softened water and require adjustment and cleaning periodically.
The needle valve I have is exactly the one you pictured but it still drifts with time so I find the capillary tube much safer. The needle and seat start to scale up even with softened water and require adjustment and cleaning periodically.
mcarroll
10K Club member
I need to try one of those fasteners, but I hesitate to drill a hole for it....might clean the spot really, really good and try superglue.
You run about 3x to 4x time the TDS of our tap water, so I wonder if that figures in to why your valve tends to clog but mine has never had that kind of issue at all?
I can't recall if I've measured my waste line's TDS specifically, but the tap runs around 200-250 ppm.* I think I've seen you post something like 800 ppm in the past. Once that's concentrated into the waste line of an RO system, that's a big pile of TDS! Dang....Now that I think about the numbers, I should run my RODI waste line to AZ....it may have lower TDS than your tap water!
* Getting a handheld EC meter soon, so will have fresh measurements! On a budget and still deciding which meter...please PM any recommendations!
You run about 3x to 4x time the TDS of our tap water, so I wonder if that figures in to why your valve tends to clog but mine has never had that kind of issue at all?
I can't recall if I've measured my waste line's TDS specifically, but the tap runs around 200-250 ppm.* I think I've seen you post something like 800 ppm in the past. Once that's concentrated into the waste line of an RO system, that's a big pile of TDS! Dang....Now that I think about the numbers, I should run my RODI waste line to AZ....it may have lower TDS than your tap water!
* Getting a handheld EC meter soon, so will have fresh measurements! On a budget and still deciding which meter...please PM any recommendations!
My softened tap TDS is around 560 lately, it changes with the seasons, demands and source blends since it is a blend of several surface water sources and treatment plants. It can be as low as maybe 500 and go well over 800 at times. Other parts of the Phoenix metro area can go over 1200-1600 TDS so I feel lucky!
To make the waste worse, I am using a Spectrapure MaxCap UHE ultra low waste RO/DI currently set at slightly less than 1:1 waste ratio so the concentrated brine or waste is pretty high in TDS, well over 1000 most days.
Even when I was using a normal RO/DI at 4:1 waste ratio the brine was still in the 700+ range though. I use a 0.2 micron absolute rated sediment filter so the brine is more dissolved solids and not suspended solids but still can clog a needle valve.
I use and recommend the HM Digital COM-100 TDS/EC meter. I have had mine over 7 years and love it. I keep a HM Digital AP-1 TDS meter as a back up and still have two of the dual inlines I never use but can turn on in a pinch if I want a ballpark reading.
To make the waste worse, I am using a Spectrapure MaxCap UHE ultra low waste RO/DI currently set at slightly less than 1:1 waste ratio so the concentrated brine or waste is pretty high in TDS, well over 1000 most days.
Even when I was using a normal RO/DI at 4:1 waste ratio the brine was still in the 700+ range though. I use a 0.2 micron absolute rated sediment filter so the brine is more dissolved solids and not suspended solids but still can clog a needle valve.
I use and recommend the HM Digital COM-100 TDS/EC meter. I have had mine over 7 years and love it. I keep a HM Digital AP-1 TDS meter as a back up and still have two of the dual inlines I never use but can turn on in a pinch if I want a ballpark reading.
mcarroll
10K Club member
Your RODI system must be mad with plumbing and valves in order to take samples everywhere. No? 
that can nearly double the cost of a system if you let it but I may still do the same when it comes time to rebuild my current system.
that can nearly double the cost of a system if you let it but I may still do the same when it comes time to rebuild my current system.
I stick a 1/4" tee and ball valve between the membrane and the first DI then another between the two DI canisters so I can monitor tap, RO only, first or MaxCap DI and final RO/DI effluent. My UHE is a nightmare or plumbing anyway with all the solenoid valves, control modules and booster pump so it fits right in. Tees and ball valves are cheap and good to have if you really want to monitor each stage or component like I do.
I haven't found a reliable salinity tester or probe so stick with my refractometer for that. I looked at probes for my Reefkeeper a long time ago but didn't like what I was seeing available.
I borrowed a Thornton benchtop lab grade conductivity meter for awhile but gave it back, just didn't use or need it I found out. When I have lots of SPS and LPS I don't use kalk but use a Geo calcium reactor instead and control pH with the Reefkeeper Lite and a pH probe suspended over a specimen container hanging on the side of the sump that the effluent drips into. I'm mostly softies and zoanthids at this time so don't even use the reactor for the time being.
I borrowed a Thornton benchtop lab grade conductivity meter for awhile but gave it back, just didn't use or need it I found out. When I have lots of SPS and LPS I don't use kalk but use a Geo calcium reactor instead and control pH with the Reefkeeper Lite and a pH probe suspended over a specimen container hanging on the side of the sump that the effluent drips into. I'm mostly softies and zoanthids at this time so don't even use the reactor for the time being.
