what gf do you use and why

[Nasser]

It's also worth noting that different versions of the Buhlmann GF algo may give different results... even using the same flavor may vary depending on how it's implemented by the manufacturer.

For example, on one of my favorite mobile apps ZHL16-B is the algo provided and typically I might dial a 25/75 GF. However, when running the desktop version of MultiDeco using ZHL-16C which is more conservative, I might dial in a 40/80 GF setting to get similar runtimes... and on the Petrel Deco Planner which also uses ZHL-16C, I have to dial in something like a 45/90 GF setting to match up the run times. So it helps to indicate which version of the Buhlmann algo is being used and even by what manufacturer.

Anyway, the settings indicated above seem to be working well for me and strike a balance of not being overly conservative and getting me out of the water safely and feeling ok.

 

[rongoodman]

30/70, since that what my Petrel and Prism controllers came set up with and I haven't seen reason to change them.

 

[kensuf]

Actually I dive different GF's - we all do! Just because you dial in a particular number does not mean you dive it unless you ascend at 30 ft/min and do perfect stops (preferably one foot stops)

I think your second question, the "Why" is the more interesting one. Will I dive a 90/90 on a 600 ft dive? Should I dive a 30/85 on a 350 ft dive with a bottom time of 45 minutes?......Think about those questions instead. Why would a given setting actually matter on DIFFERENT dives? What do you know about tissue saturation and how to manage those different tissues. What tissues are you trying to manage on a given dive? THAT's what should determine your GF. Who cares what everybody else dives. Just look at all the different answers you are getting here.

What about Helium penalties? When does it matter to account for Helium being present in the mix? Does it matter for sub-saturation dives?

In closing I will state that MORE IS NOT NECESSARILY BETTER when it comes to deco. The WHERE however does.

Aside from the helium penalty bit (unless we are talking about in your wallet), there is some good stuff in this worth repeating.

To answer the OP, "It depends, and it depends on the dive."

 

[Michael Guerrero]

Normal for me is 50/85 on ZHL-16C. I haven't been diving enough lately to up the GF Lo to compare. The why is because I've found the last decade or so of research a more compelling argument than the alternative.