BLUE KANGAROO gave the best answer that I have read on this subject so far. He/she has received clarity about an otherwise bullshxt drill that the various agencies require student divers to perform in the open water. These buoyancy drills, like fin pivoting and hovering in a sitting position should be confined to the pool. There is absolutely no practical reason to do these types of drills in the open water.
In the open water, the agencies should be requiring their instructors to take the students on several underwater tours. Dive touring underwater is how students realistically learn proper buoyancy, and not with fin pivots nor vertical hovering.
I love teaching students the pool skill of starting from the bottom of the pool from a kneeling position, and adjusting your B/C inflation until you can just touch the surface of the water from underwater in the pool without popping up through the surface. This is mostly a breathing skill. Slow, deep breaths, exhaling completely, inching up ever so slowly with perfect buoyancy, letting your natural breathing do all the work.
In the open water, whether lake, bay, or ocean, the bouyancy challenge is totally different. Now you must control your descent while clearing your ears and establish perfect neutral buoyancy BEFORE you reach the bottom of the ocean/lake. BEFORE. You should not crash into the sea life on the bottom and kick up a big cloud of dust and disrupt everything that lives down there.
Then once you achieve perfect neutral buoyancy at the start of your open water dive, then you have to maintain it all through your dive, by adding or subtracting micro amounts, squirts, of air to or from your B/C, and again by controlling your breathing, nice deep breaths, slow, inhaling and exhaling comletely.
That is perfect buoyancy.
As Herman added, proper weighting is going to be the key to good buoyancy as well. Hopefully your instructor spent some time with you at the end of your first open water dive, adjusting your weighting in the open water, so that you only just barely have enough lead on you to keep you neutral at the end of your dive, during your safety stop, when most of the 5 lbs of equivalent negative buoyancy of compressed air that you started with in your tank is now gone, exhaled by you into the ocean/lake. Any more lead than this absolute minimum is going to make achieving perfect neutral buoyancy impossible.
Proper breathing, proper weighting, and proper use of bursts or bleeds of air into/from your B/C is what will give you perfect neutral buoyancy in scuba diving.
