I wouldn't trust it since it doesn't look like there is anything in the middle to hold the tank. Looks like the middle could easily crack with a 200lb tank.
well i have a place i can put the 10 gallon. i have a custom built stand that will hold it underneath. the only bad thing is trying to do water changes with it so close to the ground, but with it being my killifish tank i can probably just take a bowl and scoop the water out, but then i dont know where to put my quarentine when im using it. UGH!. also my desk is holding 2 10's right now does it look like its good enough to hold 20 gallons?
Think of it this way, dude... with all the time, effort, thought and money that goes into a tank; do you really want to risk it by putting it on something that was never meant to hold that much weight over a long period of time? Seems to me to make better sense to ask your grandfather to build you another stand.