Hi Ivan,
No worries ......no one is born learned.
Equalizing with water that is high in microorganisms (tropical) could lead to infections if you were to get it in the middle ear. I only fill the sinuses and nasal cavities. Water never enters my middle ears. To ensure this doesn't happen one should have some estimate of one's sinus and nasal volumes. That info. can be gotten in specialist anatomical textbooks. From there you can then work out calculations on pressure volume relations as they relate with depth.
Some might be willing to let water enter the middle-ear, e.g., Stepaneck but the depth limiting factor isn't ability to equalize but ability to tolerate high hydrostatic loads on the venous system and heart muscle, i.e., you could blow a main if blood pressure rises high enough.
You can reduce the risk of SWB by reducing your initial lung volume. As you know they call it shallow water blackout happens (usually) in the last few meters where the pressure gradient is steep. For example, in ascending from 10m to the surface your lung volume will roughly increase two twice the volume. Lung gas must re-expand and/or be 'sucked' out from the circulation for this to happen. If your initial lung volume is say, 4 liters at 10m then by the time you reach the surface this will have expanded to roughly 8 liters, i.e., twice. The greater the change in volume the greater the potential suction effect. If the change in volume is great enough enough O2 could be removed from the circulation to drop arterial oxygen pressure. Now, if the change in volume is small as for example when doing an exhalation dive then so too will the suctional effect.
Glottis is that part of the anatomy which blocks air moving from mouth to lungs and vice versa; as when you hold your breath. The soft plate is that part which opens and closes when you breathe, or not, through your nose. Osmosis is to do with solutions and their concentrations such that the constituent of a solution seek to move from areas of high concentrations to areas of low concentrations and thus gain balance, e.g., pruning effect of the skin when you've been in say, fresh-water too long.
If it still doesn't make sense and if your in Cairns on Thursdays I'm usually at the Woree pool from 11.30am onwards. Feel free to drop by or give us a call the night before (Tel: 40 511150) so that I can confirm that I'll be there. Don't know what you know or don't know but if you feel you might get some benefit from doing a no nonsense session with me, feel free.
Seb
Townsville, Aust.