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.