sump question

i bought this sump awhile back ago and i tryed to put it up. i didnt come with instuctions because it was custom made by some one in austion i had one of my aunts buy it from craigslist. well anyway its a 20?gallon tank with bio balls and a some a pump and a filter. i but it all on but it just drained my tank. then i turned the filter off and let the pump go on by its self its but the water back it. having the filter on and the pump off is the same as the first problem. but faster....am sorry its reversed lol. it added to much water into my tank because i had but about 10 gallons of fresh saltwater. any help i well try to get pics soon.

 

.bump.