help with RODI system.

[LeftyReefer]

Are you flushing your (new) carbon filters before installing the RO membrane? New carbon blocks can shed carbon fines into your ro membrane if you don't flush them first.

And are you opening the flush valve on the membrane for 10/15 minutes before closing it to produce water?

I'd check the seals on the membrane and make sure they are all seated correctly too.

 

[cst0215]

Thank you for the input. I did flush the new carbon by disconnecting the line entering the RO membrane and connecting the output line to it. I did notice carbon fines exiting this flush line.

I have been flushing the RO membrane before use. Tonight I flushed it for at least a half hour, then closed the flush valve and made clean water for an hour and noticed no drop in TDS.

I checked the seals and they appear good, will check again.

Could I possibly need to clean the system with bleach? (Excluding) the filters, resin, and membrane)

I also thought maybe the drain line was back flushing into the membrane so I installed a check valve. It did not improve anything.

Perhaps a new membrane housing?

 

[LeftyReefer]

There are instructions for cleaning your RODI system, posted on the Buckeye Hydro site.
Sanitizing your RODI

 

[Freenow54]

64% rejection is definitely way too low, especially with a new membrane. Since you already changed the membrane and checked that it’s seated correctly, I’d check the waste-to-product water ratio and the pressure going into the membrane next. Also make sure the flow restrictor actually matches the 75 GPD membrane. If pressure and waste ratio are good but you’re still seeing 127 TDS after the membrane, I’d start looking at the membrane housing or seals/O-rings for bypass

I remember Randy Holmes talking about a customer of his , or friend . Especially if your flow is low , as well as the tds meter placement being wrong , Maybe you have bacterial build up . I wonder if you can flush it with peroxide . I am not sure maybe others could comment on a check valve issue

 

[Freenow54]

Thank you for the input. I did flush the new carbon by disconnecting the line entering the RO membrane and connecting the output line to it. I did notice carbon fines exiting this flush line.

I have been flushing the RO membrane before use. Tonight I flushed it for at least a half hour, then closed the flush valve and made clean water for an hour and noticed no drop in TDS.

I checked the seals and they appear good, will check again.

Could I possibly need to clean the system with bleach? (Excluding) the filters, resin, and membrane)

I also thought maybe the drain line was back flushing into the membrane so I installed a check valve. It did not improve anything.

Perhaps a new membrane housing?

I see my suggestions were already being addressed sorry

 

[LeftyReefer]

Truthfully, I've never heard of that off-brand of RO membrane before. I've purchased RO membranes off Amazon too, but I always get a Dow Filmtec membrane, not an off brand.

Some of the reviews for that membrane sound like others have had the same experience you are.... so I would ditch that membrane (can you return it?) and get a real Dow membrane.
FilmTec membrane on Amazon

 

[bristleworm]

Do you have your TDS sensors installed correctly? They have to be perpendicular to the flow not parallel. The water has to flow through the posts, not over them.

 

[cst0215]

I have verified that the 2 sensor probes are perpendicular to the housing (I can see both probes, they are not in line.

 

[cst0215]

Today I thought I found the smoking gun…I was missing the o-ring that sits in the cap of the membrane housing. I bought a new mousing and tds on the out side of the system is still in the 50s.

I did notice my house water supply is 70 psi. Could this be causing the high tds since I think I read that the optimal pressure is around 50 psi?

 

[LeftyReefer]

No, RO membranes actually work better at higher psi.

My RODI system runs at 90-100 psi with my booster pump running.

 

[cst0215]

Ok. Good to know. Thank you. I’m learning a lot, but this is really frustrating.

 

[Freenow54]

Do you have your TDS sensors installed correctly? They have to be perpendicular to the flow not parallel. The water has to flow through the posts, not over them.

Pardon Me ? Can you post a photo of your Probes ? Even the make of them , but preferably where the manufacturer states this . The reason I ask is that mine are not built like that. Also BRS instructions say perpendicular

 

[Freenow54]

I have verified that the 2 sensor probes are perpendicular to the housing (I can see both probes, they are not in line.

maybe time needed to flush the system ?

 

[Freenow54]

Do you have your TDS sensors installed correctly? They have to be perpendicular to the flow not parallel. The water has to flow through the posts, not over them.

You answered your own statement maybe you meant it correctly but the flow through statement paints the wrong picture

T I know its upside down for explanation but water flows across the top , the probe is put in the upwards facing opening. ie perpendicular . Flow is around the probes

 

[cst0215]

When the probe is installed in the fitting it came with it is a “t” with 2 inlets in line with each other and the third opening at a 90 degree offset to the other Two. The probe is in the latter. When I look thru the 2 inlets that are in line with each other I can see both of the probe electrodes like looking straight on to a field goal. Is this correct?

 

[Freenow54]

When the probe is installed in the fitting it came with it is a “t” with 2 inlets in line with each other and the third opening at a 90 degree offset to the other Two. The probe is in the latter. When I look thru the 2 inlets that are in line with each other I can see both of the probe electrodes like looking straight on to a field goal. Is this correct?

Yes

 

[cst0215]

Also had an idea last night…. Could I plumb 2 RO membranes into the system? The first membrane would knock the tds to around 60 ppm and the second would take care of the remaining tds before going into the di resin. If this is possible, any help with how to do the plumbing would be great. Just not sure how to do the waste line…. Would I install a restrictor on each line and then use a 3 way fitting to join them into a single line going to the drain? Thank You

 

[LeftyReefer]

Bristleworm's explanation seems correct to me.

The sensor has 2 metal probes on the end. Those probes need to be inserted so that they are perpendicular to the flow of water, not parallel with the flow.
You want the water flowing through/between both probes, not going around both probes.

the attached picture should be how the probes are oriented in your water line.
When looking down the water line, you should see both probes like shown below. If you only see one probe, then it's parallel to the flow and needs to be rotated 90 degrees.

 

[bristleworm]

Also had an idea last night…. Could I plumb 2 RO membranes into the system? The first membrane would knock the tds to around 60 ppm and the second would take care of the remaining tds before going into the di resin. If this is possible, any help with how to do the plumbing would be great. Just not sure how to do the waste line…. Would I install a restrictor on each line and then use a 3 way fitting to join them into a single line going to the drain? Thank You

Yes, running two membranes in series is a very common practice with a lot of advantages. There is a BRS series on how and why to do it.

 

[EricR]

Also had an idea last night…. Could I plumb 2 RO membranes into the system? The first membrane would knock the tds to around 60 ppm and the second would take care of the remaining tds before going into the di resin. If this is possible, any help with how to do the plumbing would be great. Just not sure how to do the waste line…. Would I install a restrictor on each line and then use a 3 way fitting to join them into a single line going to the drain? Thank You

Personally, I'd think you'd want to first figure out why your current setup isn't producing anywhere near normal results from the single RO membrane.