RO/DI question

[Treebeard]

I have an Aquasafe unit with 3 DI resin canisters which has been in use for about a year. A couple of months ago I changed all three filters and the resin because TDS was creeping up in my water and the output was getting very low. The instructions indicated that the RO membrane should last for at least two years so I did not change it. However, my output was still low and I could not get TDS below 10ppm so last night I changed the RO membrane as well. Now things are even worse. I cannot get TDI below 15ppm and the flow restrictor which is supposed to put back-pressure on the membrane seems to have no affect.

Which component of the system reduces TDI? Is it possible my that my resin is contaminated and needs to be changed again?

[hillegom]

Do you mean you have 3 DI resin canisters in addition to a particle and carbon canisters?
Depending on the type of membrane you have, the carbon protects the membrane from chlorine. Some DI resins change colour when exhausted, so it is easy to see how close to the end you are.
The flow restrictor has to be matched to your membrane, ie a 100 gpd membrane has a different restrictor than a 50 gpd unit.
What is the tdi or your feed water?

[Treebeard]

There are three particle and carbon canisters, followed by the RO membrane and three DI resin canisters. I think the resin is supposed to change from green to brown when it is exhausted, but it always has looked brownish to me.

I am not sure about the flow restrictor. I ordered the replacement membrane from the same place I ordered the system, so I would assume he would send the correct replacement membrane. The restrictor is adjustable, but even setting it wide open in flush position, there is still water coming out the clean water line. With the old membrane opening it all the way would result in zero output. Closing it all the way would result in maximum output with dirty water.

I cannot recall what the tds is of the raw water, but I am guessing it is around 50ppm. I will check it at lunchtime.

Do you mean you have 3 DI resin canisters in addition to a particle and carbon canisters?
Depending on the type of membrane you have, the carbon protects the membrane from chlorine. Some DI resins change colour when exhausted, so it is easy to see how close to the end you are.
The flow restrictor has to be matched to your membrane, ie a 100 gpd membrane has a different restrictor than a 50 gpd unit.
What is the tdi or your feed water?

[Myka]

What's the TDS of your tap water?

Can you take a picture of your unit (oh that sounds bad!! :o ), or provide a link to your exact one? As hillegom pointed out, I'm wondering if you have confused the DI cartirdges for particulate and carbon filters. The order should be: particulate, carbon, RO, DI. Once the water passes through the RO it should not be greater than 20ppm or it will exhaust the DI resin very quickly, and will not get it down to 0 ppm TDS. Try disconnecting the hose feed between the RO and the DI and test the water coming out of there (collect it in a clean cup for ease of testing). If it is greater than 20 ppm or approaching 20ppm I would suggest you add a second RO cartridge. This would probably only be a problem if your tap water has really high TDS which is very possible where you live.

EDIT: You have a 7 stage filter system? There is no reason to have a system that large for tap water with a TDS of 50 ppm. My tap water is 90-95 ppm, and my 4 stage (particle, carbon, RO, DI) gets my product water to 0 ppm TDS. I am wondering if your adjustable flow restrictor is faulty...I have never seen one of those before, and I am leary about how it may work.

[Treebeard]

I will try to supply a picture when I go home for lunch.
I have the order exactly as you stated below. It is possible that I exhausted the DI resin because I did not change the membrane at the same time I changed the resin and particulate filters, but the guy from Aquasafe said the membrane should last for 12-24 months.

I will also test the raw water and the water after the membrane.
It is a 7 stage filter, if I understand correctly. There are three canister filters, followed by the RO membrane, followed by three DI canisters.
I agree with your comments on this adjustable flow restrictor. It is a real pita to set correctly. What kind of system are you using?


What's the TDS of your tap water?

Can you take a picture of your unit (oh that sounds bad!! :o ), or provide a link to your exact one? As hillegom pointed out, I'm wondering if you have confused the DI cartirdges for particulate and carbon filters. The order should be: particulate, carbon, RO, DI. Once the water passes through the RO it should not be greater than 20ppm or it will exhaust the DI resin very quickly, and will not get it down to 0 ppm TDS. Try disconnecting the hose feed between the RO and the DI and test the water coming out of there (collect it in a clean cup for ease of testing). If it is greater than 20 ppm or approaching 20ppm I would suggest you add a second RO cartridge. This would probably only be a problem if your tap water has really high TDS which is very possible where you live.

EDIT: You have a 7 stage filter system? There is no reason to have a system that large for tap water with a TDS of 50 ppm. My tap water is 90-95 ppm, and my 4 stage (particle, carbon, RO, DI) gets my product water to 0 ppm TDS. I am wondering if your adjustable flow restrictor is faulty...I have never seen one of those before, and I am leary about how it may work.

[Myka]

I will try to supply a picture when I go home for lunch.
I have the order exactly as you stated below. It is possible that I exhausted the DI resin because I did not change the membrane at the same time I changed the resin and particulate filters, but the guy from Aquasafe said the membrane should last for 12-24 months.

I will also test the raw water and the water after the membrane.
It is a 7 stage filter, if I understand correctly. There are three canister filters, followed by the RO membrane, followed by three DI canisters.
I agree with your comments on this adjustable flow restrictor. It is a real pita to set correctly. What kind of system are you using?

I have an AquaFX Barracuda 4 stage was $180 I think. Your first three cartridges (I'm assuming one particulate and two carbons?) should be changed every 6 months no matter what. The RO should last the longest, but it's hard to pinpoint how long it will last. Be sure when you do replace it that you replace the first three just before replacing the RO. The DIs will last varying amounts of time as well given how much TDS is reaching them. Measure the TDS of the water after the RO but before the DIs as I described above, and the tap water, and we can go from there.

[hillegom]

When you change your particle and carbon filters, disconnect the feed line to the RO.
After the filters are changed, flush water through and catch the effluent. A lot of times, the water will have small particles of carbon "dust" that could screw up the RO membrane and/or the flow restrictor. When the effluent, is clear, shut off the water and reconnect the line to your RO. Possibly, you have some small particles stuck where they should not be

[hillegom]

Forgot to mention, if you have an incoming TDI of 50, a reading of 0 output is easily attainable.

[Myka]

When you change your particle and carbon filters, disconnect the feed line to the RO.
After the filters are changed, flush water through and catch the effluent. A lot of times, the water will have small particles of carbon "dust" that could screw up the RO membrane and/or the flow restrictor. When the effluent, is clear, shut off the water and reconnect the line to your RO. Possibly, you have some small particles stuck where they should not be

What he said. I should have mentioned that...sorry.

[Treebeard]

Apparently my memory is not what it once was, or maybe it never was....anyways my raw water is 276. TDS after the RO membrane is 20.
I did not have time to take a picture, but from the instructions it is a 5 stage system:


5 micron sediment
Carbon
5 micron coconut carbon
RO membrane
DI cartridges (3)


At the beginning it was reducing TDS to 0.
When I changed the carbon and sediment filters, and the DI resin, I did not change the RO membrane, nor did I disconnect and flush the filters.

Is my RP membrane ruined, or can I flush it out? As I said previously, I am also having trouble with the flow restrictor so I guess it is also screwed up. Your explanations would explain the problem.

[mark]

Have the Aqua-safe also.

With a TDS of 20 after the RO would say it's okay but your DI is probably exhausted.

If your still running the post carbon after the DI, it could be the cause of the TDS not zero. Do you have the bladder, because if that wasn't drained, might be a cause also.

Diagram here (http://canreef.com/vbulletin/showthread.php?t=46350&highlight=aquasafe)

[hillegom]

For an aquarium, your DI should be your last filter, For your drinking water, preferences vary, but I have a charcoal as the last filter for the fridge and at the sink tap

[Myka]

I have no idea what the coconut carbon filter is...???

I may have missed it, but how many GPD is your system rated for? Most RO membranes (Filmtek 50 & 75 gpd and BFS 150 gpd) are 98% efficient which means if the water going in is 100 ppm TDS the water coming out will be 2 ppm TDS when it is new, and that will slowly rise until you need to change it. The Filmtek 100 gpd membranes are only 90% efficient, so if you have the Filmtek 100 gpd this is probably not a good choice for your higher TDS source water. You should be able to replace your flow restrictor with a regular type...they are cheap. Then choose a compatible RO membrane. I would suggest either the 75 gpd or the 150 gpd if you really want, just make sure it is 98% efficient. I think you may have exhausted your DI resins, but you can replace your RO membrane, and figure that out later. Don't forget to replace the sediment and carbon filters before the RO, and flush them before hooking into the RO like described earlier. I would ditch the coconut filter...don't know what's up with that, sounds weird.

[hillegom]

I agree with Myka about efficiency
Here is what one ebay seller said about coconut carbon

Carbon Cartridges are extruded carbon block with coconut carbon. Coconut carbon is a premium carbon that gives water a great taste, and some contend a "sweeter taste."

I would think something burned to carbon is the same for all materials. What do you have left? Just carbon IMHO

[midgetwaiter]

I may have missed it, but how many GPD is your system rated for? Most RO membranes (Filmtek 50 & 75 gpd and BFS 150 gpd) are 98% efficient which means if the water going in is 100 ppm TDS the water coming out will be 2 ppm TDS when it is new, and that will slowly rise until you need to change it. The Filmtek 100 gpd membranes are only 90% efficient, so if you have the Filmtek 100 gpd this is probably not a good choice for your higher TDS source water.


This is why I don't like the Aquasafe for Alberta water, you burn through DI resin way too fast because the 100gpd membrane isn't as effective.

If the DI you had was brown from the start it might have been packaged badly. DI resin that isn't sealed will pick up CO2 from the air and exhaust it. Sounds like your flow restricor is messed too though, it should shut off the product water when you open it up.

[Treebeard]

The membrane is made my Applied Membranes. (http://www.appliedmembranes.com/tfe.htm) It is the M-T1812A100 model rated for 100gpd.

If the water is coming out of the membrane at 20 ppm, can I expect good DI resin to reduce it the rest of way to zero?

Where can I pick up a vertical DI canister?

[hillegom]

This is where I picked mine up, but there are a lot of sellers on ebay that might have them as well.
http://filterdirect.com/index.php?cPath=70&osCsid=5dd1e124f8c0e8442bfdb78bb04f5669