Your pool will work fine. No re‑creation needed.

ECC vs. non‑ECC is a memory thing, not a disk format thing. The pool is stored on drives, not in RAM. Swap the sticks, boot up, and TrueNAS will see the same drives, same zpool, same everything.

The only caveat: if your old non‑ECC RAM silently corrupted some data that was sitting in memory before hitting disk, that corruption is already there. Switching to ECC won’t fix it—but it also won’t break your pool. You just get better protection going forward.

No extra steps. No re‑create. Just a quick power‑down and swap.