Re: "Co2 bombs" for slugs.
Welding supply shops will rent you CO2 cannisters - they frequently do a small business renting CO2 to restaurants and bars. Make sure to get a regulator valve when you rent the cannister.
Seal-up the tank with painter's tape and or plastic wrap and then run the tube from the cannister into the tank. CO2 is heavier than air and will sink to the bottom of the viv - pushing the oxygen up and out.
The air coming out of the tank, especially at high flow rates, will be very cold. I wrap a cloth napkin around the end of the tube so that a jet of cold air doesn't blast one part of the tank.
I run the CO2 bomb for at least 4 hours or over night. Do that 3-4 times spaced-out by a week each time and you should be good to go.
Watch out for acid damage to your plants! Plants are resistant to damage from CO2 bombs but not immune - avoid watering immediately before and during the CO2 bomb as it can encourage damage on wet leaves.