Well, yogurt that has fermented 24 hours should be very tart. Yogurt that has been fermented for this extra long time (normal 6-8 hours) should have great reduced lactose levels, greatly increased lactobacteria levels, and greatly increased lactic acid levels, hence the "acid", or tart, taste.
Unless you add dry milk solids, which is NOT recommended for candida sufferers, home made yogart will always be somewhat thinner than the commercial product.
I just learned something. Don't let the heated milk cool off TOO much before you add the starter. That will cause thin yogurt. It also helps to preheat the yogurt maker. I was always only concerned about adding the starter when the milk was too warm. Apparently there is a temperature "window" within which the starter must be added. I had a few very thin batches lately, and come to think of it, the milk was on the cool side when I added the starter.