I have a clay pot of E tenellus that smelled like it was anaerobic, it's 4" deep. I poked it with a chopstick all over, maybe a dozen times. Then I did it again in about a week. It seems fine now. I could pull it out and smell it. I pulled out my rocks that were on top of soil, so I wouldn't have to poke under them. My MT snails weren't trying to go under the rocks that I could tell. I have regular gravel.
But If I had sand in these, I'd do an experimental poke around to see if bubbles came up. If you get bubbles, poke around more to release all the bubbles. Check it again after a while, and consider adding the other things: heavily rooted plants, Malayan Trumpet Snails. Just keep an eye on it. If you have no bubbles or bad smell, then you wouldn't need to do anything, maybe just give it a check poke once a month when you trim plants. Bubbles and smell= poke around again later.
