For long-term...

You will get better results using an airlock, after the initial air exposure of 4-8 weeks of vinegar ferment...also you will want to halt the acetification process by heating/filtering and then adding 1T 80-proof Vodka per gallon.

Also, if you use an old sherry cask, or well smoked new oak barrel, you could make your Balsamico-style vinegar. The modern way is to add oak chips to the vinegar.

Whatever you do DON't use any metal utensils when making/working vinegar - you can get away with a good quality Stainless - but best is old-school wood, glass, and stoneware...

Also a hydrometer and Acid Test kit from a winemakers supply will allow you to repeat favourite results.