RODI

[jtl]

I have been fighting a problem with my RODI for a year. I burn through RO membranes way too fast and the reason is unknown. I am lucky to get 400 gallons out of a new one and as they go south my DI resin is trying to compensate. For example I just changed the DI and after making 50 gallons it is 1/3 used. My incoming water is 210 ppm and afte the RO is is still 39 so you can see the problem. Just for reference I have researched this, talked to experts and even replaced the part that hold the membrane thinking it may be cracked all to no avail but I am still looking for suggestions. I religiously back wash the membrane and do not run hot water through it. Maybe I am just going to have to live with replacing the membrane every 7 months.

 

[Crabs McJones]

What is the incomming water temperature and pressure. Do you flush the membrane before and after each use? @chipmunkofdoom2 may be able to help

 

[jtl]

What is the incomming water temperature and pressure. Do you flush the membrane before and after each use? @chipmunkofdoom2 may be able to help

50psi in and 40psi coming out of the membrane. I do flush the system. I checked the current RO membrane is only 7 months old.

 

[JoshH]

Is this city or well water??

 

[Crabs McJones]

50psi in and 40psi coming out of the membrane. I do flush the system. I checked the current RO membrane is only 7 months old.

Is this on city or well water?

 

[Crabs McJones]

Is this city or well water??

great minds

 

[jtl]

City water.

 

[jtl]

City water.

 

[JoshH]

City water.

Do you know if you're dealing with chlorine or chloramines?

 

[Crabs McJones]

Do you know if you're dealing with chlorine or chloramines?

^^ This and what pre-filters are you running?

 

[jtl]

The temp is not over the top maybe 75 degrees F.

 

[Stonekeg]

What's the rated rejection rate for the RO filters you're using? Most standard versions for reefing should be 98% or 99% from what I understand, but I'm not 100% on that. I'd first check to make sure the membranes are rejecting everything they should be. The 39 ppm you're getting out of your RO seems really high to me, but not unheard of.

Also, are you sure the end of the RO membranes are seated firmly in their groove in the RO cannister? I've run into something like this a few times, and a couple of those were solved by just resetting the membranes.

 

[jtl]

Chlorine:1.5 mg/l

 

[Fin]

Are you using one or two carbon blocks?

 

[jtl]

I use the Dow 75 gph Fintec RO membrane.

 

[jtl]

I use a pre filter and a BRS a 5 micron Chlorine/VOC carbon block filter.

 

[Stonekeg]

@jtl It looks like your filter is awesome, and your temperature is great, too. That leaves the weakish 40 PSI as the culprit in my mind. My 2 cents? Look into a booster pump for your unit. It might save you money (in the long run) if you can't get that PSI up to at least 50ish.

 

[Crabs McJones]

I use a pre filter and a BRS a 5 micron Chlorine/VOC carbon block filter.

one pre-filter and one carbon block? my guess is the carbon block is getting used up quickly, chlorine will eat away at an ro membrane

 

[jtl]

It is 50 in, just 40 out. Well, at least with an RO filter that is not doing much.

 

[Crabs McJones]

It is 50 in, just 40 out. Well, at least with an RO filter that is not doing much.

Another question, what restrictor valve do you have on the system, any way you can share a picture of the whole RO/Di unit for us?