Do you mean that you had your tanks Hydro tested ? They still have to be VIP’d with sticker before a fill anyways. So it doesn’t matter if its full or empty. The tank will have to be empty for the VIP inspection anyways. If its a steel tank and even if a small amount of water was left inside from a hydro test. It will cause rust very quickly. Get them to the LDS for a VIP/fill. Its not a good idea to store your tanks empty anytime.