Hi Leanne, Great Tank. I would definitely replace the gravel or stones asap as Kurt said. I have large rocks in my Enclosure and on top of that I have sphagnum moss. The Sphagnum is not sitting in water and thrives in this situation. Its great for greenery. I'm not familiar with your Frog though so you may need to look into their needs first. I have a photo of my set up in my album if you want to see what I mean. I hope this has helped.