Built a stand for a 72” 125 gallon using 2x6s and 2x4s with 3/4” plywood top and bottom. The stand was level and the surface was flat when I built it in the garage but after I set the tank on it and put ~25 or so gallons of water in I noticed the plywood kind of warped downwards. The tank is supported on all four corners but the two ends have a substantial gap. Will the plywood flatten out with more weight on it or what should I do?