Skyflame 3/8" - 3/4" Red Natural Stones Lava Rock Granules for Gas Fire Pits, Fireplaces, Gas Log Sets, BBQ Grills, Garden Landscaping Decorations,Cultivation of Potted Plants, 10LB

You'll probably have to use about 4 or more bags to get enough to cover the burner ring on a 31 inch fire pit. I did 3 bags of the smaller rock and mixed in about 1/2 a bag of the 1"-3" inch. I probably could have used more, buy mine has a lid when not in use.

I purchased this item to keep the slugs from eating my plants and it worked right away. No more slugs!

3/8" - 3/4" is perfect for a chunky aroid mix. Just needs rinsed first as it comes pretty dusty.

Much cheaper than our local store. A 5lb bag cost $5, this is a 10lb bag.

Small stones only 1 inch diameter. I used my larger stones on bottom. Grill now burns hotter with gas on low.