Having an almost 100 year old house and a cobbled together "temporary" pond in the basement, moisture in the basement is often an issue. After installing a set of steel shelving and noticing the "heavy duty particle board shelves" they came with I knew that I would need a better solution than just painting the particle board. Even after a short time in the basement and at the uppermost shelf mold growth and warping were evident.
Step 1: ClosetMaid to the rescue
After trying out a few other solutions I came across these at my local Home Desperate. Closetmaid #34714 11.89" x 48" Superslide Shelves. You'll need two of them per level and at almost $6 each in CT they can add up, but if your patient you can find Edsal shelving at almost 50% off a few times during the year. I'd be curious if this works with other shelving systems.
Step 2: Lock and Load 1
Your first step is to "lock" the bent part of the wire shelf under the lip of where the particle board would have rested and then lower the rest of the wire shelf into place.
Step 3: Lock and Load 2
Then you do the same with the other wire shelf turned around. With the two shelves butted up against each other you're practically eliminating any chance of sagging.
Step 4: Detail shot
As an added precaution I zip tied the shelves together in three locations.