RO Filter Raising PH??!?

[Bullhog]

Does anyone have any experience with a reverse osmosis filter raising water PH? I have RO drinking water at home, I don't brew with it yet but was considering it. I just checked the PH and its going in at 9.6 (9.6 is normal for our city water in Austin TX) and leaving at 10.1. I changed the RO filter and same thing. What on earth is going on? I'm a using a calibrated meter, and verifying that the city water is 9.6 gives me some confidence that its not a meter issue.

 

[mabrungard]

Some activated carbon media can raise pH. Most RO systems have activated carbon pretreatment.

 

[RPh_Guy]

Water pH should be completely ignored. It is meaningless.

For checking your RO system quality you should be using a TDS meter.

 

[Bullhog]

Some activated carbon media can raise pH. Most RO systems have activated carbon pretreatment.

I checked the pretreated water as well, it is 9.6 just like the City water.

 

[Bullhog]

Water pH should be completely ignored. It is meaningless.

For checking your RO system quality you should be using a TDS meter.

Agreed, but surly an elevated ph after RO treatment is alarming, right?

 

[RPh_Guy]

Agreed, but surly an elevated ph after RO treatment is alarming, right?

No, not in the slightest.

 

[day_trippr]

Agreed, but surly an elevated ph after RO treatment is alarming, right?

As @RPh_Guy said, not in the slightest. The reason why is there is so little ionic content left in good RO product water that the intrinsic pH will be literally swamped by anything it comes in contact with that has a different pH.

If you want a compelling example, take the pH of a glass of RO water, leave it sitting open for a few days, then take pH again. Just the mere absorption of atmospheric CO2 will drive the intrinsic pH down - no minerals required...

Cheers!

 

[RPh_Guy]

Tap water pH doesn't matter either (not just for RO). Water pH doesn't correlate well with alkalinity.

 

[Bullhog]

As @RPh_Guy said, not in the slightest. The reason why is there is so little ionic content left in good RO product water that the intrinsic pH will be literally swamped by anything it comes in contact with that has a different pH.

If you want a compelling example, take the pH of a glass of RO water, leave it sitting open for a few days, then take pH again. Just the mere absorption of atmospheric CO2 will drive the intrinsic pH down - no minerals required...

Cheers!

I’m going to try this. Already feeling better! Cheers!

 

[Bullhog]

Thanks again to everyone. I bought a TDS meter and the RO water fall well within range. I also did what @day_trippr said and left my water out for a day and sure enough it soaked up enough CO2 to lower the ph to 7. All is well!

 

[RPh_Guy]

Thanks again to everyone. I bought a TDS meter and the RO water fall well within range. I also did what @day_trippr said and left my water out for a day and sure enough it soaked up enough CO2 to lower the ph to 7. All is well!

Just to be clear, you don't need to do that every time. That was only for demonstration purposes.

 

[day_trippr]

hahaha!

 

[Bullhog]

Just to be clear, you don't need to do that every time. That was only for demonstration purposes.

Haha! Yes of course. I actually don’t use it for brewing. I’m blessed with low TDS water that I use for brewing, although the RA is a little high. We get a lot of boil notices though and the RO filter helps a lot.