Understanding PH

[stickman]

Drainsurgeon, Just a quick comment about PH meter temperature correction. A typical meter with automatic temperature compensation, only corrects for the change in response of the probe at different temperatures. It does not correct for the change in PH of a solution at a different temperature. The same sample of wine will have a different PH at 55F vs. 70F.

 

[Scooter68]

Found a calculator to do the conversion if your meter does not adjust here is the difference for an uncorrected reading of pH pf 3.50:
3.50 at 60 = 3.59
3.50 at 65 = 3.57
3.50 at 75 = 3.51

Since I believe most of our fermentations occur between these temps (good luck starting a fermentation at 60f)

So it would appear that the variation is not insignificant but not earth shattering either:

Site for calculator is: https://www.hamzasreef.com/Contents/Calculators/PhTempCorrection.php

All this matters most if your room temp varies significantly between your measurements. otherwise if the room temp is steady then tracking changes in pH is straightforward.

 

[wineforfun]

My recipe was from winenoob66 called Tropical blend. There is also a Tropical Nectar that I copied from this site (didn't record from who) and both recipe's started with 2-48 oz cans of Pineapple juice. I used 6# peaches, 6# mangoes, 3# pineapples and 5 bananas. Haven't bottled yet so can't give final results. I think I got both recipes from the DB thread but that was over a month and several bottles of wine ago.

I gotcha. Yeah, those were offtakes. Dave has always used lemon, lime or acid blend in the original recipes, that is why you through me off.

 

[drainsurgeon]

Drainsurgeon, Just a quick comment about PH meter temperature correction. A typical meter with automatic temperature compensation, only corrects for the change in response of the probe at different temperatures. It does not correct for the change in PH of a solution at a different temperature. The same sample of wine will have a different PH at 55F vs. 70F.

I had to read this about 4 times before it made sense. I misunderstood the meaning of an "auto temp correcting"and thanks for clearing that up. I will find a chart for correcting for must temp but it sounds like the correcting is not real significant. Thanks.

 

[drainsurgeon]

Found a calculator to do the conversion if your meter does not adjust here is the difference for an uncorrected reading of pH pf 3.50:
3.50 at 60 = 3.59
3.50 at 65 = 3.57
3.50 at 75 = 3.51

Since I believe most of our fermentations occur between these temps (good luck starting a fermentation at 60f)

So it would appear that the variation is not insignificant but not earth shattering either:

Site for calculator is: https://www.hamzasreef.com/Contents/Calculators/PhTempCorrection.php

All this matters most if your room temp varies significantly between your measurements. otherwise if the room temp is steady then tracking changes in pH is straightforward.

That calculator is for temp correction that my pH meter already does. I need the chart that gives information for change in temp that my meter does NOT compensate for. I think.

Also, my room temp (basement) is very constant in the summer. I am amazed how much a must temp increases during an active ferment however. My Tropical Blend went from 71 to 84 in 1 day! I thought I needed to wrap the primary (with towel) to help bring the temp up. I now keep a fan blowing on the primary (unwrapped) until it gets down to 1.0. My most recent batch of DB I was able to keep the must temp down with the fan. It went from 70 to 75 during the first week.

 

[Scooter68]

Yeah the fermentation process does generate some heat. As to the temp adjustment looking at the differences I wonder if the shift would be enough to worry about. After during fermentation a lot is happening and as you know the temp is going to rise considerably at first and then taper off. If a 15 degree change results in a .08 change in pH I don't think I'd worry much initially. Wait until fermentation is completed and temps normalize then start checking. I normally check pH at fermentation start, At shift to secondary vessels, and again at end of fermentation once the must has a good clear layer on top (before racking) After that if you have a marginal pH you can check at each racking and adjust then if needed. The extent of a shift during fermentation will depend a lot on the fruit/juice being used. A prepared canned or frozen juice should be much more stable than fresh juices for fruit. If your DB is all from juice unless you get some reaction started somewhere I don't think you're going to see a dramatic swing in pH. That's from what I keep reading all over the place on different sites and different users who have done this for years.

Unless you intend to drink in the 30-60 days you should have time to adjust the pH if it starts drifting too high or low. Never seen anyone (authoritative or well experienced source) say any given wine should have a specific pH or even be withing a pH range of .10 or less. Anyone have facts to disprove, we'd all like to see that.