This recipe is an all-time favourite that i used to make for my kids and have been named:  Wurmpie-koeldrank - because of the pieces of lemon rind which float around if you use soda water in mixing.

Ingredients:

10-12 lemons or limes (lime is a bit more acidic and gives it a fresh taste which i prefer)

25ml Epsom salts

25ml citric acid

25ml tartaric acid (not creme of tartar)

2Kg sugar - xylitol works great.  I would not use erythritol as it gives it a funny taste. because the syrup is highly diluted, you might just use white sugar, as this is a treat for some days, not all day.

1.5 liters of boiling water

Method:

* finely grate the rind of the lemons/limes

* juice the fruit

* add the skin and rind to the boiled water, with the rest of the powders, acting as preservatives

* stir until dissolved - not over heat, just stirring as it dissolves easily.

* leave overnight

* next day you can either scoop away some or all of the rind, but this is where the fun comes in, as the rind bubbles up with the soda water and makes it fun to drink.

* bottle in glass bottles 

* dilute to taste - i would say about 2 T and top up with water/fizz