Odd pH problem

I've been making wine for about 5 years, but this is my first mead (traditional Sourwood mead). The recipe was simple. Approximately 10.6 lbs. sourwood honey to make around 5 gallons. Starting s.g. was 1.084. Used K1V1116 yeast. PH measured 3.98 a couple days into fermentation. A couple of days later, pH measured 3.70. Had fermentation problems. Added more yeast nutrient and a yeast energizer made from an old packet of yeast. Also added 2.75 tsp acid blend, which reduced pH to 3.49 an hour later. Added another .25 tsp acid blend for good measure. I ended up making and adding a starter and eventually got s.g. down to 1.001. Once finished, I racked and added k-meta.

After clearing and degassing (a little less than two months), I racked and added sodium benzoate. The sodium benzoate was well over 4 years old so I added a little extra. I then took a pH reading. PH measured 4.58??? I had calibrated the meter, but knowing the probe was three or four years old and the calibrating solution was several months, maybe a year old, figured the measurement was incorrect. However, I measured the calibrating solutions and was within range of what each should measure. Again, I thought that maybe the calibrating solutions were the problem. I also hypothesized that the sodium benzoate temporarily caused a spike in pH (note, I took the pH reading after adding the sodium benzoate). About an hour later, I added enough honey to get s.g. from 1.001 to 1.004 (1/4 lb of honey). I also added some French oak cubes. I tasted the mead after adding additional honey and it did taste a little flat, which I thought was likely due to tasting immediately after adding the additional honey.

Today (a month later) I took took another pH reading. This time I used a new probe, which I calibrated a few days ago with new calibrating solutions. The pH measured 4.52. Also to my dismay I discovered a little foam caused by the agitation of the wine thief. I stirred and yes, a million tiny bubbles rose up. Obviously, the old sodium benzoate didn't do the trick. I knew it might be a little risky, but wasn't too worried since even if the additional honey re-started fermentation, alcohol would only be boosted by a small amount. Figuring I needed to start getting the pH down, I added 3/4 tsp of acid blend to the 3 gal carbouy (mead is spead across 3 gal carbouy, 1 gal jug and a couple of 750 ml bottles). In a couple of days, I will rack all into primary to blend and take another pH reading.

I would like to have a pH of under 3.5 for protection and for taste.
Assuming pH is still going to be high, any suggestions as to how to bring down without going crazy with acid blend? Any thoughts as to what caused a pH of 3.49 during fermentation to shoot to 4.58 a couple months later?

I used 6 tablets of benzoate, added to around 4.5 gallons of mead. The instructions on the bottle say to add 1 tablet per gallon. I added 1 extra, knowing the benzoate was old. Also, each tablet contains 250mg benzoate so in total, I guess I added 1.5 grams. I only used because I figured there would be less chance of off-flavors with benzoate than with sorbate-- especially with this being a rather light, delicate mead.

I had no idea the effectivenss of benzoate was pH dependent. Also, I added k-meta when I racked after fermentation. I added .31 tsp (1/4 tsp + 1/4 of 1/4 tsp) to around 4.75 gallons of mead. I added the extra because I added the first 1/4 tsp prior to stirring w/drill attachment to degas. Stupid to add prior to stirring, but I just wasn't thinking. Anyway, I added the extra 1/4 of 1/4 tsp after doing all the stirring. Though I didn't measure sulphite after adding, I'm sure that even with the stirring I had 60ppm+ sulphite. Of course, sulphite is pH dependent so if the pH was high at that time, I wasn't getting much protection no matter what my sulphite levels were.

A couple days after pH measured 3.49, I added 2.5 tsp of yeast nutrient. The yeast energizer I added at the same time was simply 1 packet of expired yeast boiled in a little water. All of this was added to the original must which was around 5 gallons.

This is a really strange situation. I've never had anything like this occur with making wine. My hypothesis is that the alkalinity or buffering capacity of my sourwood mead is even less than other types. Hence, wild pH swings are occurring with the addition of anything with a higher or lower pH-- even when added in small quantities. I kept coral reef tanks for several years and without proper buffering capacity, pH could plummet at night due to no photosynthesis taking place. PH could also get high during the day due to photosynthesis (simply algae taking in CO2 and releasing oxygen with light, and releasing CO2 without light). A minimum alkalinity had to be kept to stabilize pH. If alkalinity got below that threshold, problems started. The lower the alkalinity, the more likely and more severe the problem.

If my hypothesis is correct and the alkalinity is in fact very low, it shouldn't take too much acid blend to significantly lower the pH. My hope is that the 3/4 tsp I added today might get me close. I really won't know until I blend altogether and take another reading. However if it has only a small effect, I'll be at somewhat of a loss as what to do. Obviously, some amount of acid will bring the pH where it needs to be but at some point taste becomes a big facor. Of course if pH doesn't decrease pretty significantly, this mead won't likely last long enough to get much enjoyment out of it anyway.

After reading your post, McFeeley, I did some more searches. I also found some documentation stating an increase of pH with addition of sodium benzoate. It was written in laymans terms and stated a possible pH increase of .1 - .5. It didn't base that increase on any particular amount of benzoate, but maybe a pH increase of 1.0+ is possible in my situation. I plan to rack all containers to my primary tomorrow and take another pH reading and add enough acid blend to get down to a reasonable pH range unless the alteration of taste just won't allow.

A fair question.

My reasoning is off-flavors. Right or wrong, I've seen recommendations for using benzoate over sorbate in that benzoate contributes less to off-flavors. I realize this is quite subjective and that some might be able to detect one and not the other. I feel I have tasted sorbate in wines, where the one time I used benzoate, I detected no off-flavors. Furthermore, the benzoate worked fine in regards to preventing renewed fermentation with the addition of sugar. In this case my mead is quite light. Hence, any off-flavors would likely be more detectable. Therefore, I chose benzoate.

I will also say that I RARELY add sugar post fermentation. I like dry wines so that is what I typically make. I usually don't add benzoate or sorbate on anything I'm leaving dry. I don't add a lot of finings either. I just give it time in the carbouy. I only added a little honey in this case to potentially create a broader appeal for others like my wife, who doesn't like dry wines unless they are fruity New World whites. I added honey to enhance the honey flavor, while adding an amount small enough to keep the mead relatively dry.

In the little online research I did, I found where both were sometimes used, but the reason was for additional protection. I never found where the reason was to reduce off-flavors.

I also found no reasons for using sorbate over benzoate or vice versa. The only thing I found was more anecdotal-- people on message boards recommending one over the other. I did find references to sorbate causing problems when used in wine that has undergone MLF. I also found that sorbate had a higher pH threshold, up to like 6.0, compared with the lower pH threshold associated with benzoate. Since it is common for red wine to have a pH of 3.7 or 3.8, it would likely take an additional amount of benzoate to protect (protection goes up to 4.5, but begins losing effect at like 3.6).

As far as my problem goes, I added 1 tsp acid blend at a time and re-measured pH. I ended up adding 2 tsp, which got pH down to 4.14. I added 1/2 more tsp for good measure, but didn't take another pH reading. My hope is that pH will decrease over the next month. I was also surprised my sulphites measured very low. I guess all the stirring and possibly the vacuum degassing as well as a little time took its toll. I added 1/2 tsp sulphite, which is going to be pretty high, but I need for protection with the higher pH. I also have time for it to get back down before I bottle.

Taste was ok after adding the acid. However, I haven't drunk a lot of meads so it's a little hard for me to judge. Also, the mead was full of CO2-- even after I stirred the heck out of it with my drill. I'll give it a month and check pH and taste. If pH does in fact go down, I'll probably add a little more honey. I got back down to within .001 of my pre-sweetening s.g., so all of honey I added pretty much fermented.

I'm not sure that isn't overblown. Copied from an International Programme on Chemical safety study:

Sodium benzoate is used in the treatment of patients with urea cycle enzymopathies (i.e., hyperammonaemia due to inborn errors of urea synthesis) in order to facilitate an alternative pathway of nitrogen excretion. The therapeutic dose given over several years is in the range of 250-500 mg/kg body weight per day.

Basically, it is used as a medicine at way higher dosages than what we would use in wine or mead. It might make sense to cut back on soft drinks for those who drink a half-dozen cans/bottles per day, but for the small amount added to an offdry wine/mead in the amount I'm going to consume, I'm not going to worry too much.