[spaghetti]

Originally Posted by dave

Just get in the water as much as possible, anything else is of pretty limited help for hunting. There are no short cuts, just dive a lot and your times will naturally increase
cheers
dave
Spearguns by Spearo uk ltd finest supplier of speargun, monofins, speargun and freediving equipment

Very well said, Dave. Freediving is freediving, spearfishing is spearfishing.
Increasing your CO2 tolerance for hunting is just minimal help (and possibly a danger), cause when you hunt you do not concentrate on the dive: it's no introspection, it's circumspection. You have a gun to handle, a terrain to scan, fish to seize, in short it's not the same thing at all.
Just learn to breath properly: three or four breathing acts before each dive, deep and slow breaths, with the exhale time longer than inhale time, and then proper intervals to oxygenate between dive and dive. And NEVER stretch your breath hold time to the limit while hunting: always save some "emergency" air for the case you get tangled or so. (This is nothing scientific, just a real-life amateur spearo's experience)