how to correct a problem with my sourdough starter
When there’s liquid on top your starter it past the really active stage (or you put too much water). If the liquid smells alcoholic, even more so but don’t worry, these beasties are practically indestructible.

You can rejuvenate it by adding a couple of tablespoons of the starter (after discarding the liquid) to equal weights(not volumes) flour and water. I tend to go 40g starter to 80g flour+80g water which I then use to make poolish every 3-4 days or so (which I then use to bake 2 loaves using ~500g of flour). Once I make the poolish, I remove ~40g of flour and the cycle goes on. Remember, no salt goes in the poolish(or starter for that matter)!

If you bake less frequently than every few days go slightly drier: 100g flour/60 water to 40g starter - your starter will stay active for longer but it will also taste more sour as you leave it. If you bake really rarely, like once a month, you can keep it in the fridge and rejuvenate as above a 2ple of days ahead of baking, discarding what remains of 40g. 

Finally, if you are wanting to keep a starter with rye, disregard the above- rye tends to mould more easily so you have to be vigilant with your feeds (although you can just give your starter a rye feed every once in a while to no ill effects in my experience)