How do I justify upgrades?
Until now, I've never considered that I might need to defend those decisions.
I want to make the best beer I possibly can and I want to do that with the greatest efficiency of time and effort and possibly money.
To do those things I need appropriate measuring equipment (TDS meter, pH meter, excellent thermometer), enough capacity in my kettle and burner, a place to maintain ferm temperature, a way to make starters, a way to crush my own grain (which allows for purchases in bulk which save money), a way to oxygenate the wort....
Can you make good beer w/o all that stuff? Sure. I did. But I'm after great beer, exceptional beer, and to reach that goal I've been following a strategy of continuous quality improvement. Every time I brew I try to do something better.
My "upgrade" this time was to oxygenate the starter wort before pitching the yeast into the erlenmeyer flask. I'd never done that before. The yeast took off after pitching, so it didn't seem to hurt any.
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Some of these decisions are dependent upon where we are in our life cycle. My kids are grown and out of college. I have more disposable income than 10 years ago. Fifteen and even thirty years ago, there is no way I could have afforded the upgrades I have. Or even probably afforded to brew at all, wiht young kids at home.
In the end, you justify anything using whatever value system you have. My wife loves to travel. I don't. She travels with my daughter. I stay home usually. What I don't spend on travel I set aside for my hobbies, of which brewing beer is one.
You have to decide where the best place is to put your money. Some of it is simply having something fun to do so you stay sane.