I am new to winemaking and have been using fine mesh nylon bags during primary fermentation, primarily for fruit wine. Although i have read several comments I have not seen any clear guidance. I place the bag into the primary and then add all the ingredients. Allowing the fruit to interact rather than tie the bag closed and allow it to float. Seems to provide more fruit flavor exchange. The issue is stirring the must. The bag tends to get in the way when stirring, even though punching down the cap is no problem. Has anyone heard of any glass or plastic weight rings to keep the bag expanded and near the bottom to facilitate stirring?