i had an incident the other night. my peppermint shrimp was in my overflow box,and could not get him out, so i stop the u tube flow and dumped him back in tank, but i had too start the u tube sipon again with the air hose, i attached a longer air hose so i wouldn't get any tank water in my mouth, well any way i did get it in my mouth, and in a couple of minutes, i got dizzy,faint, and very hard too breath, then was hot and cold. this lasted about 2 hr's. i was so close to going to emergency room. well any ways i waited it out and feel fine, but was very scary. i'll never be doing that again.