Well I did two small terra cotta pots. One capped with small smooth pebbles and one without. I lowered them very slowly. I had zero issues with the aqua soil spilling out.I was debating that this week too and came up with no good reason as to why not !! The only issue I could think of is when you come to submerge the pot it’ll fly out everywhere, if you gravel cap it and go slowly it should be fine though !