ro filtered water mineral content

[aussie brewer]

Hi I just changed the filters in my 5 stage ro system, flushed it and got a reading of 25ppm
my inlet water has a ppm of 98, does this sound about right?i thought the ppm should be a lot lower after ro. The ph is 6.5, im not sure what to enter into bru n water for my water profile.
Anyone have a suggestion? cheers

 

[TechFanMD]

Did you fully empty the pressure tank - is that what you mean by flush?

I would do it again. 98 down to 25 isn't great, I'd expect ~10ppm or less on a new membrane with that starting water.

For comparison, I get 23ppm with water starting at 125ppm on a 2 y/o membrane (mine is 4 stage).

 

[aussie brewer]

yep, I emptied about 5 tanks, I didn't disconnect the carbon filters from the ro membrane to flush the carbon first. I put all the new filters in and drained 5 tanks

 

[Silver_Is_Money]

Your TDS should be 5 or less.

 

[TechFanMD]

Your TDS should be 5 or less.

Do you have a source for that? Generally accepted is 1/10 of TDS in for this type of RO system.

 

[aussie brewer]

I emptied a whole tank into a rinsed bucket and now the reading is 14, good enough I hope!

 

[Silver_Is_Money]

Do you have a source for that? Generally accepted is 1/10 of TDS in for this type of RO system.

Rejection should be at least 95%.

0.05 x 98 ppm initial = 4.9 ppm final

Also, my well water reads 876 TDS, and my RO water reads 45 TDS.

 

[mabrungard]

RO membranes do require conditioning and the TDS concentration that they produce will drop during that initial startup. High initial TDS is not necessarily a bad thing, but do monitor the value to assure that it drops.

 

[aussie brewer]

RO membranes do require conditioning and the TDS concentration that they produce will drop during that initial startup. High initial TDS is not necessarily a bad thing, but do monitor the value to assure that it drops.

Thanks for the advice martin! The tds went back up to 21, will keep testing it

 

[Jayjay1976]

Membranes have a "break in" period. Give it a few weeks and check again.

 

[day_trippr]

A few weeks? That ain't right.
My 50 gpd membrane took my 300 tds well water down to a consistent 6 within the first 24 hours of use and it stayed there for a couple of years...

Cheers!

 

[Jayjay1976]

I guess I wasn't as focused on it as you were. Checked it the day of install and wasnt pleased. Checked it again 2 weeks later and at 004 I was happy. Out of the tap its ~160. YMMV.

 

[HTH1975]

We get a steady 3-4ppm TDS reading at work with untreated reading around 150-160ppm

 

[aussie brewer]

Would adding a de ionizing filter to my system give me near 0ppm water for brewing?

 

[mabrungard]

Would adding a de ionizing filter to my system give me near 0ppm water for brewing?

Yes, but its not necessary nor desirable. Deionization is totally unnecessary for brewing use. Its just another accessory that a water treatment seller wants to get your money for. Unless you need virtually ion-free water for some other use, don't bother with deionization.

 

[aussie brewer]

Yes, but its not necessary nor desirable. Deionization is totally unnecessary for brewing use. Its just another accessory that a water treatment seller wants to get your money for. Unless you need virtually ion-free water for some other use, don't bother with deionization.

Thanks Martin, I took the ro membrane back, they tested it and said they were getting 12ppm and gave me a new one, after replacing the membrane and flushing a few tanks im getting a reading of 20ppm???not sure what is going on
I used br u n water for my last brew and it predicted my pH to 0.01accuracy!! cheers!

 

[mabrungard]

A new membrane requires several days of operation for it to achieve its appropriate level of ion rejection. Don't be alarmed that it's initially passing more TDS than expected.

 

[MaxStout]

The rejection ratio should be more than 90%, hence you should be getting TDS <10ppm RO from your 98ppm feed water. In fact, many systems have rejection ratios in the high 90s. You're system is just in a break in stage. After some use the RO should have much lower TDS.

 

[Buckeye_Hydro]

The quality of the permeate will likely improve over the first 6 to 24 hours of run time.

Second, if you want to measure RO membrane performance, you need to sample the permeate (RO water) coming out of the membrane, before any taste and odor filter, and with the valve on your pressure tank closed. The back pressure exerted by a nearly full pressure tank can dramatically affect the quality and quantity of the permeate.

Russ

 

[aussie brewer]

The quality of the permeate will likely improve over the first 6 to 24 hours of run time.

Second, if you want to measure RO membrane performance, you need to sample the permeate (RO water) coming out of the membrane, before any taste and odor filter, and with the valve on your pressure tank closed. The back pressure exerted by a nearly full pressure tank can dramatically affect the quality and quantity of the permeate.

Russ

Thanks for the great info!