Water questions...pH & TDS?

[hilljack13]

I have a RO system and filled my first gallons this week to brew today. I usually use bottled spring water. The pH measured on the spring water was generally ~6.90. So today when I took to initial pH before dough in, the pH from my RO was 8.50. Is that unusually high? My TDS was 3ppm.

Also, after adding salts, my ppm showed 365. I thought that was sorta high. My pH for mash ended up at 5.4 so at least that is good. The brew was an oktoberfest-ish type.

 

[NSMikeD]

What are you using to measure pH, and what temp? Since I have a saltwater reef tank, I have a rodi unit (i.e., deionizing membrane) that scrubs it down to 0 TDS. Most units can be expanded. Also, it's debatable, but there are arguments about removing chlorine vs. chloramine and what filter the units have as the latter is harder to remove.

When I have off readings but end up spot on, I declare user error. FWIW, I really never trust my pH readings that much. I know I am starting out with a blank slate (0 TDS water), measure out the salts with a reliable kitchen scale, and malts are decent quality, so taking pH readings is overkill and can make me doubt. When I do take them, and they are as predicted, I just nod in approval and continue on, notwithstanding that I would ignore them if they weren't as expected.


ps. did you run your system a few minutes before collecting water?

 

[Genuine]

I know with my RO System, I'll let it run for 10 minutes or so before I begin collecting and Everything from the tap is designed for potable water. That helped me out a bunch. Of course after adding your salts you'll notice more PPM due to what you added so it's good that the meter is picking up on it. My old RO system brought my city water from 160ppm to 3ppm. I just replaced it tonight so we'll see what readings I get.

 

[dmtaylor]

You can't measure the pH of RO water accurately, there aren't enough ions which the pH meter needs for accurate measurement. Stop measuring the pH of raw water, especially RO or distilled water. It only leads to confusion and sometimes to bad decisions.

 

[marc1]

If you've got RO water with a TDS of 3, the pH isn't relevant for mash pH estimation.

 

[jerrylotto]

Best time to measure pH is 15 min into the mash after adding all salts to your mash water as you seem to have done.

PS - TDS is not particularly relevant after adding salts or starting your mash. All it tells you is that your salts dissolved.

 

[hilljack13]

You can't measure the pH of RO water accurately, there aren't enough ions which the pH meter needs for accurate measurement. Stop measuring the pH of raw water, especially RO or distilled water. It only leads to confusion and sometimes to bad decisions.

Yeah, I'm realizing this now.

 

[hilljack13]

What are you using to measure pH, and what temp? Since I have a saltwater reef tank, I have a rodi unit (i.e., deionizing membrane) that scrubs it down to 0 TDS. Most units can be expanded. Also, it's debatable, but there are arguments about removing chlorine vs. chloramine and what filter the units have as the latter is harder to remove.

When I have off readings but end up spot on, I declare user error. FWIW, I really never trust my pH readings that much. I know I am starting out with a blank slate (0 TDS water), measure out the salts with a reliable kitchen scale, and malts are decent quality, so taking pH readings is overkill and can make me doubt. When I do take them, and they are as predicted, I just nod in approval and continue on, notwithstanding that I would ignore them if they weren't as expected.


ps. did you run your system a few minutes before collecting water?

I have one of the apera (sp). I forget the model, but it was highly touted on another thread here. I ran the RO system earlier this week and filled gallon jugs on separate days. Tested at room temp 68-72F. I just received the RO unit last week and did run it before collecting.