Way too many variables to consider to come up with any generic guidance. Sometimes I'll add a little, especially with light color beers. Usually I don't bother acidifying. It depends on your source water, and the style you are brewing. 0.45ml concentrated lactic doesn't seem like a crazy...

I always picture beta and alpha as tools or machines, and starches and dextrins are loooong chains or in fact shrubs of carbohydrate molecules (and proteins and lipids and other things are also present but it's safe to set those aside). Beta amylase (and all the other enzymes besides alpha) are...

Exact opposite.

Step mash is ye olde brewer's way of getting around undermodified malts. Today undermodified malts barely exist anywhere -- you have to purposely seek them out or do something stupid to benefit much from step mashing. So, like I was originally going to say, step mashing in the 21st century...

In an ideal universe, I would use phosphoric. However, I am cheap and lazy. So... I use vinegar. Yes, vinegar. Not to worry, the finished beer doesn't taste sour or vinegary, not in the slightest. The amount used is so small compared with the gallons of wort/beer that it just doesn't...

I have no idea what's going on with the wild pH swings, other than either user error or the thing is broken. Those are some pretty wild swings, and end-of-mash pH of 5.9 is high but not completely unheard of I suppose.

When is the last time you calibrated your pH meter, and how did you do it? What type of calibration solutions do you use and how old are they?

Oh dear... that is an awful lot of Special B and melanoidin malt! These are extremely powerful malts. Honey malt is also powerful and sweet, but a good one to keep in there as-is. I would take the Special B and melanoidin down to about 50 to 75 grams each, no more than that. Then to replace...

Oh, but don't you know... homebrewers LOVE to make things more difficult -- and more expensive -- for no noticeable difference! :D ;) :D ;)

I always thought honey malt was just a special type of crystal malt, so I was going to say "just steep it", no need for enzymes.... but then I looked into it and some suggest that it should be mashed because it does have extra unconverted starches and even has some diastatic power of its own. I...

Mine varies a lot; HOWEVER... the pH of your water doesn't really matter, as much as its buffering power. Hard water is buffered. Soft water is not. This means, pH matters less with hard water, and more with soft water. Many (most?) waters are reasonably hard. On the other hand, it is very...

The right kinds of barley have been cultivated for so many thousands of years now that it just WANTS to be at a pH of about 5.4 no matter what we might throw at it. We almost sort of have to TRY pretty hard in order to screw it up.

It's not this exact one, but 99.9% similar. Only $21. Enjoy...

I use a cheap Chinese meter that I got on Amazon for like $15 that comes with the calibration powders. It's held calibration nicely for over a year now -- I check calibration every time I use it and it works great. Nothing beats these cheap pH meters, they work just fine, and if/when they fail...