I swear, it is always something in this hobby.
I looked in my cabinet to check my top off reservoir and noticed my pH controller was reading 6.3. This was well into the PP, so it should have been down at 5.5. Checked the pressure gauge on my regulator and saw it was reading 0 or close to it. Went to turn the knob so I could remove my regulator, and low and behold, it was tight. So, somewhere in the move I guess I forgot to reopen the tank. Oooops. Kind of explains the rather poor growth and little bit of filamentous algae I've seen pop up the last few days.
Just curious, how long do you get out your CO2 tank? I've been running the same 9 kg tank since December. I feel it getting close to the end, but who knows. The investment in a large tank is so worth it - 2.2 had to be filled every two months on my 60cm. 5 mos (who knows how long) on this 9kg tank (and 90cm aquarium) is well worth the inconvenience of filling the tank as well as the cost to refill. I've already paid for it in savings, especially as my local place charges $18 for a 2.2 fill and $24 for a 9. Don't get me started on the fuel my Toyota drinks to get there.
Another benefit is the pH controller. For the first seven years I was in this hobby I relied upon a DC and pH profiles. I never had much issue, but it did require occasional adjustments and certainly more attention, especially at the beginning of a set up. Spending $100 on a pH controller has made my life immensely easier. Set it and forget it, just recalibrate every few months. It uses less gas and keeps things nice and stable. While an investment, I think definitely a nice tool, especially for beginners, who are delving into CO2. There is inherent value in learning to tinker, create pH profiles, etc., but it makes the world much, much easier.
For someone who travels very frequently, spends a lot of time in the backcountry, and weeks away from home, certain pieces of kit make this hobby immensely more convenient. Hell, I spend less than an hour a week maintaining my tank. I can leave for a month and not bat an eye thanks to ATO, doser, and pH controller. While I hate the extra equipment and the upfront expense, it is well worth it in the long run.
And for anyone who might be new to the hobby and wondering if more expensive equipment is worth it, I say: Buy once, cry once (or twice).