Like everything else tank banging is double edged. Yes, most experienced divers hate it & consider it an unecessary disturbance to the tranquility that diving affords. I agree that tank banging should be minimized to only emergiecies, or the truely unique or otherwise missed sighting.
On the other hand, the problem for dive guides is that so many of their charges wouldn't see anything and would have disappointing dives if the DM didn't point lots of stuff out. DMs vary greatly in their ability to strike a balance in how much, how loudly, and how often to bank on their tanks. I know of some who manage by a sort of code, bang-bang means look here, critter; repeated banging means something important.
I manage to avoid some of the disturbance by diving at a distance from the main group and spotting my own photo ops. This also means that I have fewer folks kicking up silt and mucking up my shots. The drawback is that, while spared the noise, I might miss out on some stuff because the local DM is usually a better spotter than I am.
BTW- tank banging is only one nuisance on dives, computers alarms have gotten louder and there are more of them, so the ends of dives are starting to sound like clock stores at noon. And coming soon: underwater walkman, whose earphones are sure to provide high quality background music for all to share. Isn't technology wonderful?
