It's very tasty but too sweet. I reduced sugar to 1 cl and used Dry tonic and it still was too sweet. If you're using a regular sweet Tonic, I would recommend to use no additional sugar at all.
I tried it with no sugar, and it was very refreshing, though I used organic grapefruit, which I’ve found to be much less tart than normal grapefruit, so the level of sweetness may have evened out.
I agree original spec was a tad on the sweet so like you I've gone with 10ml sugar (2:1) but with standard quality tonic water (Eager). The glass size and amount of tonic also plays an influence and with a 12oz Collins glass I used 50ml tonic so I have added this detail to the recipe above.
Anonymous