The purpose of racking mead is to separate the must from the lees (the sediment that forms during fermentation). Lees can influence the flavor and character of the final product; this can be good or bad depending on the variety of yeast and your personal tastes. Removing the sediment also improves the appearance of the final product.
At least twenty-four hours before you plan to rack the mead, elevate the fermentation chamber to a table or chair and raise one side of your fermentation chamber so that it is sitting at an angle. This needs to be done ahead of time so that any sediment stirred up has time to settle before racking. The elevation is necessary so that gravity can be used to transfer the mead from the primary to the secondary fermentation chamber. Sitting the chamber at an angle reduces the amount of must left behind in the primary fermentation chamber. Once your racking equipment has been cleaned and sterilized, you are ready to rack your mead.
Lower one end of the tubing into the secondary fermentation chamber. The hose should rest on or near the bottom of the fermenter because we do not want to aerate the must during transfer. Slide a pinch-type hose clamp over your tubing so that you can control the flow of must before attaching the auto-siphon. Gently lower the auto-siphon into the must and aim for the lowest point possible without disturbing the sediment. Pinch the clamp so that when you raise the auto-siphon’s plunger, must is drawn into the column. Release the clamp and slowly press down on the plunger. This will begin the transfer of must from the primary to the secondary fermentation chamber. Use the clamp to control the speed of the transfer and remember not to disturb the sediment.
I typically check the gravity after racking to see how the mead is progressing. If there is excessive head space, it is acceptable to add some spring water to the must. Adding water will affect your gravity readings, so you should take another reading to gauge the impact. Seal the fermenter with a sterilized air lock and store it in a cool dark location. The length of secondary fermentation varies, and it is okay to rack the must as many times as necessary to separate the mead from the lees. When you are satisfied with your mead, it is time to bottle.