I have a limited quantity of sponge filters from in a cycled tank or tub. This can be purchase with purchase of an axolotl. I include instructions on how to cycle your tank using these. Real axolotls cycled these sponges and it makes cycling your tank easy and fast in roughly 2-4 days! Small is for 1-20 gallon tanks or tubs and large is up to 60gallons.
You will need to purchase the airline tubing, and air pump to hook up the sponge filter. You will also need Seachem Prime and Stability. All of these available in the starter kit as well.