You mentioned that you had used a Netti pot for nasal and sinus irrigation. The Netti pot uses passive gravity to move the buffered saline solution. Several published studies have shown that pulsatile positive pressure buffered saline irrigation is the most effective technique for nasal and sinus irrigation. That is usually what ENT's use in their offices. Water-Pik has a nasal adapter for this purpose. The Hydro Pulse® Nasal/Sinus Irrigation System and Grossman Hydro-Pulse Nasal/Sinus Irrigation System are also available. They cost about $80 and up. The problem for divers is that the pulsatile irrigation equipment is bulky and requires electric power, not exactly convenient on a dive boat or dock. A woman told me a few years ago that her Water-Pik for chronic sinus problems took up the space in her luggage that would have gone to shoes on liveaboards. She was ecstatic to find a more portable and light-weight squeeze bottle device.
There are several manufacturers of high volume positive pressure buffered saline irrigation systems: Nasaline Nasal Rinsing System (a big syringe with nasal adaptor), SinuCleanse Squeeze (bottle), NeilMed Pharm Sinus Rinse Bottle, Be-Well Nasopure Nasal Irrigation, NasalCare Nasal Irrigation, Fagor Ocean Complete Sinus Rinse for Irrigation, Breathe-ease' XL Nasal Wash System with Lavage bottle, SaltAire Sinus Relief Dispenser Bottle, and others. They cost in the $12 to $30 range and are very portable. Availability varies from store to store. None require a doctor's prescription.
For scuba and free divers the pulsatile equipment is considerably less convenient than the syringes and squeeze bottle devices which are light-weight and require little luggage space. Most of the systems have packets of dry sodium chloride and sodium bicarbonate in the right proportion to produce a buffered saline solution when mixed with distilled water. Obviously, divers will not be carrying heavy premixed solution bottles in their luggage.
Several years ago I did a trial of NeilMed Pharmaceutical's Sinus Rinse bottle kits with divers who had been using decongestants frequently when they dove. Their need for and use of decongestants dropped significantly when they began doing irrigations pre-dive. In North Carolina, where I practice, many of the local allergists and ENT's and family physicians recommend irrigation for their allergy and sinusitis patients. Many of my psychiatric patients have those problems and are pleasantly surprised with the relief they get from irrigation. After all, I am a head doctor.
Financial Disclosure: Dr. Colvard is a consultant to NeilMed Pharmaceuticals, the manufacturer of SINUS RINSE™, and has represented them to the dive industry. He has been on the speaker panel's of Bristol-Myers Squibb and other pharmaceutical companies. He has been a clinical investigator for Astra-Zeneca, CIBA-Geigy (Anafranil), Abbott Laboratories (Sertindole),ORGANON USA (Remeron), GlaxoSmithKline (Lamictal), and NeilMed Pharmaceuticals (SinusRinse).