I would not cover any vent holes. They are needed for a proper air exchange especially during lockdown.
So, these aren’t really vent holes or part of the vent system. These openings are for the auto turner, but are still present in the lower priced manual system. I bought mine last year to be a hatcher for staggered hatches, but could not get the humidity anywhere near high enough for hatching. I ended up talking with a
Brinsea engineer who assured me that the holes were meant to be filled (with the turner) and that if I wanted to run it without the turner, then the holes need to be taped up.
I’m still using it as my hatcher as needed, and for that purpose, I both insert a moist piece of sponge (it’s yellow in the pics below) into the turner tube and tape the opening at the top. There are still two other vent locations that maintain airflow and I leave those open. I also add water at the side where
Brinsea intends water to be added. With all of that, the humidity ranges from 60-75%. When it’s closer to 75% I remove some tape from the turning tube. As the humidity drops, I add water to the sponge and cover the tube opening again. I just ran downstairs and grabbed this photo, plus moved the new pearl pied keet into the brooder with its earlier hatched clutchmates. I have a continuous thermometer/hygrometer that shows the temp and humidity during the day (dipped a bit low at 59%), spiked as the keet hatched, then plummeted when I opened the incubator to remove the keet.
Sydney, you don’t need the humidity anywhere near this high right now, so if you are able to maintain temp and humidity with the turner tube open then it won’t matter if the tube is open or closed. I don’t have the turner on this model, but if you are getting it, I imagine it will fill the space anyway.
Brinsea was also really great with customer service if you want to call or email to talk with them about any incubator issues.