so i just got this 30 gallon aquarium from my uncle. he gave me all of his old stuff and what not... as i was looking at the filter system, i noticed there was on of the filter container missing. it is supposed to have 3 containers that interlock, but one is missing... is there anyway to use something else? like a food container and put holes in the bottom of it and cut it out so it looks like a filter? iono what to do. thankyou