RODI DI short life

[gearhead]

I just recently started making my own water I have very low ph like 6.2 from my well water. It comes into input at about 80ppm leaves ro at 6ppm and di at zero. After about 100gal of rodi water, I start to see 1ppm out of the di output. Then quickly starts to rise from there. I know why the di cartridge is failing so soon it's from the low ph. But wow that seems fast to me. Anyway does anyone use their water past zero ppm or soon as it hits 1ppm don't use the water?

 

[Amboss72]

I’ve seen many people use water past zero ppm. Including fish stores that are selling rodi water for profit. I have tanks using top off water that is 16-60ppm. As I’m sure you’re aware when the DI resin is spent your tds readings can sky rocket. However, water that’s just running through three stages, ending with an ro membrane typically don’t sky rocket as fast. Clearly zero tds is ideal. When I run the gamut of water outside the range of zero tds I simply don’t know what’s entering my aquarium with that tds number associated. Save yourself trouble down the road and just buy DI resin in bulk. On another note make sure you’re flushing the ro membrane for 5-10min prior to running water through the DI resin. I also turn the water off to my rodi unit entirely when my makeup water containers are full.

 

[Silver14SS]

What's the pressure? Is it a new system or used? 92% rejection rate out of the membrane isn't good.

 

[JoshH]

I just recently started making my own water I have very low ph like 6.2 from my well water. It comes into input at about 80ppm leaves ro at 6ppm and di at zero. After about 100gal of rodi water, I start to see 1ppm out of the di output. Then quickly starts to rise from there. I know why the di cartridge is failing so soon it's from the low ph. But wow that seems fast to me. Anyway does anyone use their water past zero ppm or soon as it hits 1ppm don't use the water?

What kind of system do you have? And your DI failing so soon is more likely due to CO2 in your well water (Very common problem for those with wells). Being that it's a new system I'm willing to bet your PSI is exceeding low given the poor performance of your membrane. I would check your PSI and see if you can wrangle up a booster pump to help your membrane out. This will help your DI case but not completely resolve the issue as it won't help with the CO2. You might be able to run multiple DI stages which might prolong the inevitable swapping out.

You will find people that have multiple DI stages will, once there product water reaches 1ppm, move there last stage of DI forward and replace it with a fresh batch while tossing there very first stage. This lets the first stage of not so perfect DI take the brunt of the higher TDS before being polished by the last stage.

 

[gearhead]

The pressure is between 45-50 psi. What I should have said was the water coming from my tap is 80 ppm not sure what it is going into ro cartridge. It goes threw .5 micron sediment and carbon block before the ro. It is a four stage specture pure.

 

[JoshH]

The pressure is between 45-50 psi. What I should have said was the water coming from my tap is 80 ppm not sure what it is going into ro cartridge. It goes threw .5 micron sediment and carbon block before the ro. It is a four stage specture pure.

If you have 80ppm coming from your tap, that's more than likely what's going into your membrane, sediment and carbon filters do not typically remove much if any ppm if your new Spectrapure system is putting out that much from the membrane I would call Spectrapure, something is seriously wrong. Maybe the membrane dried out somehow before installation or something. Your PSI, while on the lower end of things, shouldn't be effecting your performance to that degree.

 

[Silver14SS]

Agreed, call Spectrapure and they'll get you straightened out. They are exceptionally helpful, the owner may even answer the phone when you call.

 

[Hallowhead]

Get a better membrane. What's the TDS before the membrane ?

 

[JoshH]

Get a better membrane. What's the TDS before the membrane ?

TDS into the membrane would be in around 80 as mentioned above. For being a relatively new system and being a spectrapure the membrane performance is certainly WAY off. Which is why it was suggested to call Spectrapure, it will probably get him looked after at no or little cost vs purchasing a new membrane

 

[gearhead]

So you're saying that it putting out 6ppm out of membrane is too high going into di.

 

[JoshH]

So you're saying that it putting out 6ppm out of membrane is too high going into di.

It's not that it's too high per say, it's that with 80 ppm going in and 6 coming out, something is seriously wrong with the membrane as it is performing (Rejection rate) is right where most would throw it out and replace it. If it is indeed a newer membrane it shouldn't be performing this badly. I run a dual membrane Spectrapure setup with 240ish TDS going in, and 0-1 coming out of the membranes.

 

[Amboss72]

In JoshH situation where he’s running dual membranes with incoming water with a 240ish tds and a 0-1 post membrane tds I think that has a lot to do with him having the good fortune of dual membranes. I have clients rodi single membrane systems with 240ish tds running into the membrane and 6-9 tds out of the membrane at a psi of 40-60. These systems are running directly to the tanks float valve top offs. This may be a given but I haven’t seen anyone else share it yet. Make sure and open your flush valve for a good 5-10 minutes to rinse off the ro membrane prior to running the water into the di resin chamber. This will prolong the life of the di resin particularly if your just filling up top off water cans for use water changes. I also shut the water off to my rodi unit after my cans are full. My unit has an auto shut off valve but for whatever reason turning off the water completely has added life to my di resin.

 

[JoshH]

In JoshH situation where he’s running dual membranes with incoming water with a 240ish tds and a 0-1 post membrane tds I think that has a lot to do with him having the good fortune of dual membranes. I have clients rodi single membrane systems with 240ish tds running into the membrane and 6-9 tds out of the membrane at a psi of 40-60. These systems are running directly to the tanks float valve top offs. This may be a given but I haven’t seen anyone else share it yet. Make sure and open your flush valve for a good 5-10 minutes to rinse off the ro membrane prior to running the water into the di resin chamber. This will prolong the life of the di resin particularly if your just filling up top off water cans for use water changes. I also shut the water off to my rodi unit after my cans are full. My unit has an auto shut off valve but for whatever reason turning off the water completely has added life to my di resin.

Certainly not because of the dual membrane setup, My dual membranes are set up in series so my first membrane deals with 240TDS and the second actually deals with higher than 240 because it runs off the waste water of the first one. My high rejection rate is a combination of things, One, I forked over for Premium membranes and Two, my system runs at 85-90 PSI.

I do agree for optimal membrane and DI life Flushing before AND after is very important. Flushing the membrane before (5 Minutes should be plenty) helps prevent the high TDS creep from hitting your DI (As you mentioned above). And after to flush as much particulate matter off the surface of the membrane as possible to help prolong your membrane life.

I will add that plumbing your RODI setup directly to your setup with a float valve is not only a potential disaster if not planned for in advance with multiple redundancies in place. But it will VASTLY decrease your systems longevity filter wise.

 

[Amboss72]

Yep my bad. The dual membranes reduce your systems amount of waste water. Yes if I plump the rodi systems directly to a float valve there are inherent risks. I didn’t mention the rodi plumbed to the tank goes through a solenoid that’s hooked to a timer that only allows the solenoid to be open for the amount of time. The water then goes to the aquariums float valve. There are leak detectors next to the sump that immediately shut water off if necessary.

 

[Camaro Show Corals]

What rodi unit do you have?

 

[Amboss72]

I work with many different systems. It really depends on how old the clients setups are. Everything from old school 3 stage spectrapure setups, 4 stage Kent marine maxima hi-s to newer tanks that mostly have BRS 6 stage units.