Home made yoghurt update

I have been making my own yoghurt for a while now, was making it with shop bought soya milk and it was not a problem, ok so it doesn't thicken as much as shop bought yoghurt but it has nothing added to it. It set well enough to use, it did not separate and it tasted fine, and at a fraction of shop bought prices.

But having been given a milk maker by Keimling it seems a shame not to put this to its full use and do it all myself. For some reason I was finding that the milk was separating out when turning it into yoghurt. I know if you leave it to long any yoghurt will separate but I was finding the milk was separating before it turned into yoghurt and only the top layer was changing to anything remotely use able and I was having to strain it off. If I made 2.6 litres of mlk ( 2 batches) to turn into yoghurt then getting approx 1.5l of use able yoghurt (approx 9 standard size). Using soya beans this was working out at 28p for 9 yoghurts plus a few pence for electricity and a bit for adding sweetener/sugar/flavouring was working out at about 50p, I cant buy 2 for that price. Nut if I can stop the milk from separating then I have approx 15 yoghurts for the same 50p...less than 4p a yoghurt/

I have worked out if I use half shop bought and half home made milk then I get better results, will minimal spoilage. So I ask myself what is the difference between shop bought milk and mine. Some have apple juice in...so I tried that but no luck.
I have tried using natural sweetener instead of sugar, and again some improvement but not enough.
The other difference is a stabiliser, the say gellan gum is a good one

Mechanism of action of Gellan gum:

Gellan gum is a multi-functional gelling agent can be used alone or in combination with other products to produce a wide variety of interesting textures.  Gellan gum acts as a thickening or gelling agent and can produce textures in the final product that vary from hard, non-elastic, brittle gels to fluid gels. The formulation adopted was a gellan solution containing calcium chloride (as a source of Ca2+), and sodium citrate, which complexes the free Ca2+ ions and releases them only in the acidic environment of the stomach. In this way, the formulation remains in liquid form until it reaches the stomach, where gelation of gellan gum is instantaneous. 

and from this I worked out that agar flakes and gelatine must be roughly the same idea. So earlier on today I made milk and whilst heat treating it I added 2 tablespoons of agar flakes  and 2 tablespoon of sweetener to see if it makes any difference. Hey presto I have a batch of yoghurt which did not separate out at all, and has just been removed from the slow cooker ready to go in the fridge. I seems to taste alright, well as alright as warm yoghurt can anyway.

Tomorrow morning will tell!!