New face mask is not working!! Help!!

I have been using a CPAP for about a year. I have a DreamStation and use a ResMed AirFitN20 Nasal mask. It's one of the few that actually fits me. However, I need something for when I can't breath through my nose. I have allergies and sooner or later I'm going to get a cold. So I tried a bunch of full face masks and none fit until I stumbled on the ResMed AirFit F30, which covers the mouth and just the bottom of the nose. It fits pretty well and doesn't seem to leak much, but my sleep quality is horrible. I've been wearing an oxygen sensor and last night I had 18 times when my O2 went below 90%. I feel horrible today. My question is do I need to change the pressure because it's a different mask? I know the DreamStation has different settings for masks too, but I can't find out which one to use for the F30 or if it'll even make a difference. Any suggestions much appreciated!!!

Also - with the F30 face mask the CPAP machine does not auto start like it does with the N20 nasal mask. Is this normal?

Thanks!

One thing you have to change when you change mask types is the mask type in your CPAP setup. This Compatibility List shows what the mask setting should be for each ResMed Machine-Mask combination. I would assume if you use a DreamStation you would use the same settings as for an AirSense 10 machine. There are only three mask setting specified; Full Face, Nasal, Pillows. The AirFit F30 uses the Full Face setting. And surprisingly the AirFit N20 uses the Pillows setting. The mask type setting compensates for difference in the amount of purge flow each mask uses.

For the occasional nasal congestion I use an Otrivin nasal spray. I try to only use it infrequently and in one nostril.

Thanks Sierra. I'll check out the list. There are mask settings on the DreamStation but they are just numbers that correspond to Phillips products and it's actually hard to find what number to use for a ResMed mask. All I know is that the AHI numbers are WAY up with this mask.