It was a 21 period Hull MA. There was no subjectivity to the slope change. Sierra Chart allows you to color the MA based on slope, for example, green for up and red for down. In fact, it also allows you to color the bars based on the slope of an MA which makes things much clearer. When I say "the slope changes" I mean from up to down or vice versa, not from steep to shallow or whatever. Sorry if that wasn't clear.
The comment on the volume bar size settings that ProfLogic uses is taken out of context. His strategy involves several charts that provides a fractal view of the market. The size of the volume bars (fractals) are chosen so that a faster chart provides a "good" magnification of movements in a slower chart. Sorry for posting off topic.
That does shed a little more light on the question. But doesn't answer it completely. Why would prime numbers, odd, even, natural, complex, Fib, squares or any other number be better than any other though for choosing tick or volume chart sizes?
You'll have to ask ProfLogic about that. My understanding is that there isn't anything "magical" about it. Let say you need 10 series of charts, you could pick 10, 100, 1000, 10000 etc, or go with 7, 7*7, 7*7*7 etc like PL. Based on a prime number and maybe his backtests showed that to be a good fit? Anyway, if you're going to use CVBs, pick numbers that make sense to you (fast, intraday, swing etc).
They allow one to look at the chart in a different way. However, I am not saying it's better than time based charts. I use time based charts since most traders use them, and I want to see what they are looking at.
OK. How is a constant volume chart based on prime numbers "different" than a constant volume chart that's based on some other number? Say a 1,009 vol chart vs a 1,000 vol chart? I wasn't asking about time vs constant volume.
The difference being the prime number indicator worked with prime number charts. However, since I don't use the indicator because as noted I don't like how it shows data in real time, I only use time based charts right now. Are there magic numbers? Probably not since I also don't use Fibs anymore either since while you can see a chart where a fib worked, another chart may show that fib failing and a different fib working, or all of them breaking. However, that is not to say numbers don't matter. I experiment with my indicators and time frames to find the best system to be able to make a decision on how I want to trade something.