[bluespotjawfish]

IMHE, I don't think you need to remove the LR, just supplement it. I think you should keep enough of the old stuff (LR and some sand) so you don't have to go through a tank cycle. I wouldn't bury the existing sand with the new, it will suffocate it. When I replaced my sand, I kept about a fourth of it, rinsed it well with fresh SW and mixed in the new sand, then put my LR back in (after I cleaned it with a brush in existing tank water). The tank didn't cycle after that and my old LR is not preventing me from keeping the nitrates and alk where they need to be. I would then continue with large WCs until the nitrate and/or alk is where it should be. Make sure the magnesium level is correct and that the calc is raised in balance with the alk in the meantime. Keep an eye on your pH too. If you keep the existing wet/dry going with the bio balls for another few weeks, that will also help it not cycle. You can then slowly remove the bioballs, etc. While all of this is going on, purchasing a good skimmer and getting some more LR cycled in a tub is a good idea. Also, I'm not sure if you have already indicated this or not. Do you use RO water? If not, check the alk level in your tap water.