Update: Traps are working, but with some unexpected results.
Update to my original post.
I don't really ever post on social media, but the last post got a lot of attention and I want to be helpful - so here's a long ass post (with not great grammar) with maybe too much detail, but I'd rather give you all the information and you can do what you want with it.
After the original post it was cold and windy for a few weeks which is normal for early spring by the coast. Early on I was mostly catching asian tiger mosquitos. They're supposed to be attracted to the scent packet that I was using so that made sense.
Maybe it was too cold and the Culex (typical / common mosquito) weren't attracted because it was too early in the season, but to my disappointment the two CO2 tanks didn't make a difference. I saw more Culex mosquitos, but only a few. It got better though.
Once it warmed up this (video) is what a typical "catch" looks like in the morning. Those are all mostly Culex.
I ran out of CO2 and haven't refilled yet because the amount I've been catching has been a lot. I'll try it again now that it's warmer and I know the Culex are out and active.
I moved my second trap over to this side of the yard (it's the shady side of the yard) about 10ft from this one and it also catches the same amount. My neighbor doesn't maintain their gutters and there are big arborvitae trees along our fence line where the mosquitoes like to rest in the shade so this is an ideal placement.
There is one other thing that I've done which seems to be making a difference also. The Biogents site / documentation says the CO2 is what attracts the Culex mosquito and I've been catching mainly Culex, but without the CO2 tanks.
I do have a CO2 source though - there's a dunk bucket right in the middle of the traps where mosquitoes have been laying eggs - lot's of eggs. The scent of the decomposing leaves and the larvae make it an attractive spot to lay eggs. It's been there for about a month and a half and it stinks. I also have another one on the other side of the yard. I might add more because the amount of eggs being laid is pretty insane.
Apparently after laying eggs they go look for another blood meal.. having the traps next to the dunk bucket with scent packets (which mimic human sweat/scent) is probably why I'm catching so many without the CO2?
So far, I'm happy with the set up. Still see mosquitoes in the yard, but definitely less. The real test will be summer.