Not a specific mix I have tried, but I do like a lake and leam combi for skimmers. To keep it together, it would need to be stickier. You could try adding grey leam to help it bind, should still break up quickly. You could also mix it with one of the sensas aromix liquids, this will make it stickier and therefore hold together better. Given the depth of water you don’t want it too heavy, or too too sticky as you’ll want it to break up quickly.
A sticky mix I use on rivers is secret, brown crumb and superoach, if it’s good enough for Scotthorne.