Back to the original question...
I have some experience (at least 4) with high gravity mead (above 1.150) musts, which leads me to these thoughts:
- The higher the OG, the more difficult it will be to manage the fermentation, and it will require more of your attention (at least daily)
- The must pH should be monitored daily, and promptly adjusted if needed
- Daily infused pure oxygen is essential - during the first 3-4 days
- Staggered nutrient additions are essential
- Fermenting at elevated temperatures helps (73-75°F)
- The up-front addition of potassium bi/carbonate is helpful
- The use of yeast hulls is helpful
- A larger amount of properly rehydrated dry yeast will be required (15-20 g)
- Use one of the following yeasts: Uvaferm 43, EC-1118, Pasteur Champagne, K1V-1116
The highest SG must I fermented was 1.174. I pitched 20g of
Superstart (distiller's yeast), and it took 52 days to get to 1.044 (17.9% ABV)... After 352 days this mead remains aging in a carboy at 1.044. I expect to bottle it later this year.