Just want to throw in that, although you can drill the bottom of your tank and it can work, drilling the side/back would be a better idea. If the back of your tank cracks, you've got a chance that it will crack in such a way that your tank will still hold enough water that your livestock can survive long enough fro your to get them into another tank, while if the bottom cracks, it's bye bye nemo. The bottom is also more likely to crack, and more likely to crack in a way that your water will drain out quickly, due to the weight on it.