RO/DI help

[Fishfinder]

I cannot seem to get this problem fixed. My TDS coming into my RO/DI is 1000. My TDS coming out of my RO is 50. From there it goes to my DI. My final water has a TDS of 0-1. But I am burning through my DI resin very fast. I will test for CO2 tonight when I get off work. Could I put another RO membrane inline before it gets to my DI resin? Would that help save my DI life? Any suggestions are appreciated. I had a water company come out. They told me that my softener is working and taking my calcium carbonate levels from 374ppm down to 34ppm. But that does not affect TDS because the softener exchanges calcium carbonate ions with sodium ions. So my TDS before and after the water softener are the same.

HELP!

 

[AllSignsPointToFish]

I think the only options you are left with are to really aerate the water with outside air before the purification steps or to add a second RO membrane before the DI resin.

 

[AllSignsPointToFish]

Do you know what kind of membrane you're using? Is it a TFM?

 

[Fishfinder]

Its a DOW Filmtec 75GPD membrane

 

[Fishfinder]

I have no problem adding a second membrane. If that's what I have to do, I can live with it. Would I have to add a booster pump between the membranes? Or can I just plumb one in?

 

[AllSignsPointToFish]

The Dow membrane is a good one. How old is it?

What is your well water supply pressure?

 

[Fishfinder]

my supply pressure is 60psi. the dow membrane is almost new. it made 35gal then my Di resin burnt up. that's all it has made

 

[Fishfinder]

@AllSignsPointToFish thank you for all your help

 

[AllSignsPointToFish]

my supply pressure is 60psi. the dow membrane is almost new. it made 35gal then my Di resin burnt up. that's all it has made

Okay, good. Just eliminating variables.

 

[AllSignsPointToFish]

60 psi is probably adequate. Once the while system is hydraulically full, you should be okay. Do you have the ability to boost well water supply pressure if needed?

 

[Fishfinder]

I could do that, but I have no way of measuring the pressure after the first membrane

 

[Frop]

Coming out of the membrane it's reading 60ppm

The TDS on my well is over 1000

I had a similar problem.

I was getting 80-120+ TDS after the RO @ 65 psi. I could even boost to 100psi that made it a little worse interestingly enough. My street TDS is 800. After the water softener is 670. So my DI killed over in under 50 gallons.

This is what I had to do. I replaced all my 5 micron prefilters with .5 spectrapure. Replaced my Melev's Reef 150GPD 93% rejection RO with spectrapure 99%. The whole thing was basically the price to buy another small RO unit but my TDS is basically 8-10 after the RO.

http://spectrapure.com/FILTERS-MEMB...ystem-High-Capacity-Cartridge-Replacement-Kit

http://spectrapure.com/FILTERS-MEMB...-SpectraSelect-Plus-Tested-90-GPD-RO-Membrane

 

[Frop]

I could do that, but I have no way of measuring the pressure after the first membrane

Do you have dual RO membranes? I heard you should only run 1 if you're over 300TDS.

 

[AllSignsPointToFish]

I could do that, but I have no way of measuring the pressure after the first membrane

You won't need to measure the pressure, and even if you did, it wouldn't tell you much. If the production rate is acceptable and the quality is good, that's all you're really looking for. You can always adjust supply pressure to compensate somewhat.

 

[AllSignsPointToFish]

I had a similar problem.

I was getting 80-120+ TDS after the RO @ 65 psi. I could even boost to 100psi that made it a little worse interestingly enough. My street TDS is 800. After the water softener is 670. So my DI killed over in under 50 gallons.

This is what I had to do. I replaced all my 5 micron prefilters with .5 spectrapure. Replaced my Melev's Reef 150GPD 93% rejection RO with spectrapure 99%. The whole thing was basically the price to buy another small RO unit but my TDS is basically 8-10 after the RO.

http://spectrapure.com/FILTERS-MEMB...ystem-High-Capacity-Cartridge-Replacement-Kit

http://spectrapure.com/FILTERS-MEMB...-SpectraSelect-Plus-Tested-90-GPD-RO-Membrane

Higher supply pressure on a single membrane only forces more dissolved solids through the membrane. That is why you saw the outlet TDS increase.

 

[Fishfinder]

I'm running 1 micron sediment and 1 micron carbon before that. So I will get another membrane and see if that fixes my problem. thank you for the help

 

[AllSignsPointToFish]

I'm running 1 micron sediment and 1 micron carbon before that. So I will get another membrane and see if that fixes my problem. thank you for the help

Just keep in mind that you will most likely lose a lot of purified water from the first membrane. You may find the water quality is acceptable, but the waste is not. If that turns out to be the case, you may need to recycle the waste water from the second member to increase recovery.

 

[Frop]

I'm running 1 micron sediment and 1 micron carbon before that. So I will get another membrane and see if that fixes my problem. thank you for the help

Also to help save your DI watch out for TDS creep. When you turn on the system the startup TDS is a lot higher than running TDS. I usually bipass my DI and send the first cup or two into the waste bin.

Do you have dual RO membranes? I heard you should only run 1 if you're over 300TDS.

Still wasn't sure if you had two. But having more can effect DI if your TDS is too high.

@1:25

 

[Fishfinder]

Will CO2 in water show up in TDS? I was told that you can test ph and alk to come up with the CO2 in the water. I had a ph of 7.0 and and alk of 14. According to what I saw that puts my CO2 around 50ppm. Does that sound plausible?

 

[Frop]

Will CO2 in water show up in TDS? I was told that you can test ph and alk to come up with the CO2 in the water. I had a ph of 7.0 and and alk of 14. According to what I saw that puts my CO2 around 50ppm. Does that sound plausible?

@Randy Holmes-Farley