fermentation rate indicator

When making one`s own wine, the fermentation rate can for the most part be estimated by counting the number of times the level of the (sterilising) liquid in the air-lock rises and falls as a result of the C02 which is produced. Towards the end of the fermentation process however, the level tends to `jitter` somewhat, so that accurate measurements are not possible. One solution to this problem is to employ two electrodes, one of which is mounted higher than the other -see figure 2. The differ-ence in height between the two shou Id be greater than that by which the level of liquid fluctuates (approx-imately 2 mm).