root problems

i have a hydro that has a 5 gallon bucket, with four net cups on the top containing my plants and the growing medium,, the plants are like two weeks old the roots are growing threw the cups and are like two inches away from the submersible air pump i am fearful of the roots growing around the air pump. it scares me case i will have to change the water in like five days, and when i do if the roots are attached to the pump it could rip them off.. is there some kind of net shit i can put around the bottom of the net cups? or something to put in between the net cups and the pump to where it can still get bubbles threw but the roots won't grow on the pump.. immediate feed back would help me out