Loose fitting lid of my primary, how big of a problem? (pic)

This is my first Hefe brew and I used 3068 with only 2" of head space. To top it off while looking for my lid that came with this bucket I stepped on it and cracked it. The only alternative was this shipping lid. As you can see it's not very air tight. How big of a problem is this for me? Should I wipe it down and wrap a roll of duct tape around it or something? Even with the leak I'm still getting nearly 3 bubbles a second from the blowoff, so it's not like it's 100% open to the atmosphere. What do you think?

I'd just let it go as is & spray it good with starsan when the fermentation slows down and when you're ready to open it up to rack it. Make sure your blow off tube is just under the water, less pressure needed to push the CO2 out.

During primary, all you really are doing is keeping "stuff" from falling into the fermentation. The CO2 positive pressure given off during fermentation will keep any air out. I'd make sure that the blowoff doesn't get clogged. Hefe yeast are pretty active and it could pop the lid right off the bucket.

A more airtight setup in needed during secondary/bulk aging to keep O2 from oxidizing the beer when there isn't a positive pressure of CO2 escaping. A hefe won't need a secondary and should be drank young anyways.

Looks fine to me.

your good there is a layer of co2 protecting your beer and once that goes down as long as no dust particles can get in then your good.

Cool thanks. Right now I've got it in 65F and Friday or Saturday I'm moving it to 75F. Clove/Banana profiling. Do you think it's going to get a lot worse at 75F?