Planted Tank Guru
Join Date: Jan 2010
Location: Contra Costa CA
Removing the biggest debris, perhaps fallen leaves might be the limit, or gently moving just the surface with the chopstick idea would be the limit of what I would do.
Thriving plants will add oxygen to the substrate, so any mulm that finds its way deeper into the substrate will actually decompose pretty well.
I think that doing smaller frequent water changes will be the key. Do them often enough that the parameters do not really change. You are keeping things like the GH, KH and TDS stable with the water changes.
In a non-planted tank, or a tank with non-rooted plants (Anubias, Java Fern, Bolbitis...) you probably should work over the substrate a bit more aggressively, but as noted above, caution not to stir up enough stuff to trigger an ammonia spike. This means working over a smaller section in any one session, then coming back in just a few days to do another section. Much easier if you have rooted plants. They do a lot of the work for you.