Hi Bearson. Welcome to the forum. I am new so don't rely on anything I say! hehehe Hopefully, someone with more experience will answer you. However, from what I am learning dry ice is not a good idea. Not sure why. It seems to me that stores on the internet are recommending oxygen absorbers (very inexpensive) and mylar linings or bags (a little on the expensive side but if it preserves your food and keeps the critters out then it's worth it, imo). I hope Straight Razor sees your post or maybe you could send him a private message. I am learning so much from him through his posts and videos. He's my go to guy and my HERO. Oh, and Josiah puts out some really good info also. Lots of folks do so I'm sure you'll get better info than what I say. I just thought I'd tell you to please hold off until some others get a chance to reply.
Well, if you use dry ice, make sure to let it "melt" BEFORE sealing the container, otherwise, BOOM! The purpose with this method is that the dry ice melts and the gas is heavier than Oxygen so it fills up the container and drives out the Oxygen, then you seal it.
Most folks stopped using dry ice years ago, a few years after mylar liners and oxygen absorbers came into common usage.
Flushing with dry ice is still not going to provide an oxygen barrier or light barrier to your buckets. Mylar and o2 absorbers WILL do that.
If you have NOT worked with dry ice before, I don't recommend it. It can be dangerous if not used properly, and not just in the sense already mentioned with the "don't seal your lid for a while" thing.
Watch this before you do anything-
This is how the preparedness industry packs "Superpails." No professional packing house uses dry ice or DE currently.