Septoria issues in greenhouse3

In regards to Septoria, many molds are in the plant and when you clone you carry them forward. You might grow to just develop seeds from our current stock and see if that eliminates hour problem. The other ting that you should consider is to eliminate all soils and portable items from your property. Use a set of coveralls and shoes only for going into your green house.
The easiest method to get seeds is with silver. It does a good job and you get about 98% feminized seeds.
As far as the CO2 is concerned, if you are replacing the air often and have adequate air movers you do not need the added expense.