ok so i kno i can get away with cycleing a tank in about 24-48 hours BUT i need it done in about 30 mins! i just set up a back up grow tank. i have used the old gravel that was kept in a bucket the top layer was dry (heard it can be poisonous) but the deeper the bucket went the wetter it got. i filled it with the dirty water from my larger established tank. i have the same HOB filter on both systems. should i switch out the black sponges from the filter? or maybe just one? am i even doin the right things what can i do. oh yea and i dont have no money to spend since i just cashed out on the tank! thx 4 ur help.