I bought an easyio and some natural and greek sachets. Now I make the yoghurt from scratch using this method
Variation 2 UHT milk, 2 spoons of easyio mix, 2 spoons of milk powder and shake it up. Makes it much cheaper to make yoghurt than a whole sachet each time.
I find my yoghurt started becoming runny as the weather got cooler so I leave the yoghurt longer and replace with boiling water every few hours.
Comes out nice and thick, not gritty at all.