Add Some Indian Tonic, is a really nicely balanced tonic, with just the right amount and combination, of sweetness, acidity and bitterness.
This tonic is very well suited for the classic (London) Dry Gins, or as a mixer for Sloe Gins as well.
Only thing you need to be aware of is, that the Tonic has very little carbonic acid and very small bubbles - so you need to be very carefull when pouring the tonic, if you want to preserve the bubbles.