[wkndracer]

Hey Homer,
Coming back to this string after thinking about it today.
Long term (relative term) I always add more substrate (a clean layer).
Over the course of a year on my two hi tech tanks when areas of crypts filled in. Added maybe 1/4 - 1/2" along the back as plants became larger and over an 18 month period I've done it twice. Adding a little cap allowed me to 'freshen' the tank in crypt groups and around micro swords where vacuuming always seemed to damage the plants or loosen some. The bacteria doesn't seem to be affected enough to hurt anything and plant growth improves for about 3 months.

Part of the reason I posted 2" on a new set up is over the years it seems at one point or another I add some no matter how much I start with. Once a tank is set up I rarely (actually only remember once) completely break it down to start over.