I have Edsal shelves, but honestly, they're kind of scary. They hold the weight as long as it is evenly distributed. Mine hold a lot of weight. I have two heavy load bearing shelves on one rack, the ground level has 2 10Vs and 2 10Hs and the next has 2 20vs, 1 5 and 1 10. The second shelf was bowing a little and a tank started leaking, which wrought havoc on the particle board. I put another shelving piece down beneath the tanks and that has worked well to stop the bowing and spread the weight. I have another rack that holds a 10g newt tank (full of water) a 20L with lots of stuff in it, a 10g and 20g on the middle shelf and my tortoise and a small fish tank on the bottom. If you don't want to buy new shelves consider having some plywood cut to fit instead of the particle board. That being said, you really aren't putting that much weight down so I wouldn't be too concerned.

~Alex