take everything out. yank the sand completely. put the LR in so that you can get a siphon around all of it. then enjoy the tank. every water change siphon out the accumulated detritus. in about 3-4 months your detrital amount will be significantly less than it was when you first started this process. at this point you can yank everything out again and put sand back in if you want.

if you do put sand back in make sure that you elevate all LR so that the LR does not touch the sand at all.
LR comes to you already full of phosphates. it is just the nature of where they collect it. finding truely
cured LR is not easy. actually the stuff that the LFS is prolly selling for the least amount of money is prolly the most cured stuff they have. the less growing on it the better. back in the old days they did not sell the stuff that everyone is clammoring for. it was considered not ready, and pollution hazard. you had to wait a few weeks before the LR bins became available.
G~