I got a 125 gallon tank for a steal which has dual side overflows and i don't want to fill it up all the way until i know my floor can support the weight (2nd Story Apt) But i was also thinking about maybe using it as a turtle tank and then i'd fill it about half way up anyways. i was just wondering if i drilled holes in the overflow where i wanted my water level to be at if it'd effect it in any negative way because i cannot think of any really...I've built overflows for my 55 gallon as well as sump as well etc. Maybe i could just make another pvc pipe overflow and run it down to the wet/dry instead of drilling into the side overflows ?