Start with a diluted vinegar solution 1 part vinegar 2 parts water. If this is not sufficient simply increase the level of vinegar in the cleaning solution. If necessary you can even use straight vinegar.
Be sure to rinse the tank with a small amount of the vinegar solution and be sure to clean the area around the white valve in the bottom of the tank. Look for any calcification, salt, or mineral deposits which might form under the valve. You can easily remove the valve for better cleaning. It is also advisable to wipe down the outer housing after each use to ensure any salt residue is kept to a minimum.
Insert the vinegar solution into the handle opening where the Sinus tip is inserted and allow to soak for 20-30 minutes.
Fill the water tank halfway with the solution and place the sinus tip inside the water tank so that the solution will recirculate and run for 60 seconds.
Remove the tip so the handle is empty, fill the water tank with warm water, and hold the wand (handle) over the sink without a tip in place. Turn the unit on and allow the water to come out of the handle. Push on the pause control button on the handle a few times to loosen up any residue that may have formed in this area as well.
Soak the sinus tip itself in the vinegar solution to remove any mineral deposits which may have formed within the tip as well. You can remove the silicone bulb for better access to the stem. Be careful to pull the nasal bulb slowly straight off so as not to break the stem.
Following the steps outlined above will in most cases eliminate any residue which may be contributing to some clogging which can reduce or interrupt the flow rate and ensure proper operation.