So after 2 days of finding the majority of my fish dead apparently from an overdose of CO2, I took the advice of a forum member and ran my aerator all day and overnight to push most of the CO2 out of the tank.
I was also advised to then re-inject CO2 into the tank at a rate of 1 bps until my new drop checker arrives and I am doing that since yesterday after going back to a lime wood diffuser and resetting the Azoo CO2 regulator to +/- 30 psi. If the CO2 was the cause I believe that the Azoo regulator and the Archaea high pressure ceramic diffuser are not compatible.

This morning at feeding time I noticed clusters of small white egg-like balls stuck to several areas of the tank including the inside glass and the filter tubes? I don't understand this since I only have 2 plattys, 6 harlequin rasporas, 5 cory cats, 2 - 3 oto cats and 1 clown pleco left. After the aerator ran most of the day and night with no CO2 injection the remaining fish appear to be back to normal.
Have some of these fish begun to breed or is this something I should be concerned about?

Thanks again to all responders.

Sounds like Cory eggs. Mine put them out every few weeks. If you have any males and they fertilize them, you could get some fry.

I think your diffuser is compatible but without the drop checker it is hard to say how much CO2 was going in the tank.