are you referring to the new or old version tabs. old or new pan?
A gallon of water is about 8lbs. so there is your guide of weight.
I think the new pan holds about 2 gallons? i forget. but the bigger part of the problem with water and it falling through was how the water could slosh around if you nudge the smoker or but it when refilling. i would guess there's less of a chance of that happening with sand.