Am I doing it right?
So I've recently started a sourdough starter, and it's just over a month old now, but I have a few questions for those of you with more experience. I started it with plain wholemeal flour, it was the middle of winter (not ideal for starting a starter, I know) but since I live in a tropical climate, it wasn't really winter, my kitchen sits at around 20C. 100g each of flour and water, left in an open jar on the kitchen counter until it started bubbling, I then added another 100g each of flour and water, leaving it until it was nice and bubbly again. At this point I discarded half and added 50g each of flour and water, which has been my standard for every feeding since, it was a bit slow to take off (I won't bore you with the details) but now it's doing fine, I continued feeding it with wholemeal for about 2 weeks (twice a day, as always) discarding half at each feeding. After the two weeks I simultaneously started, slowly making the transition to white unbleached bakers flour, and keeping half in another jar in the fridge. At this point it did slow a little, but is still quite alive, it never seems to quite double in size after a feeding though.
Now as far as I know, I've done everything right up to this point (please let me know if I haven't) I've never missed more than one feeding at a time, and it's always bounced back very well.
Now for my questions :)
I've begun slowly transitioning my feed to a mix of wholemeal, rye, and white flour, as my breads are often a mix of any of these 3, is this ok?
the one time I've actually used the starter I've been keeping in the fridge, I used it straight from the fridge, which I now know is wrong, as the process of making the dough, letting it rise, knocking back and letting it rise again took almost 24 hours, if not longer! (delicious results, but a much denser bread than I was expecting). How exactly should I be using the starter from the fridge?
It's been suggested by a chef I work with (who has limited knowledge of bread baking, in fact I seem to know more than him about some things) that I mush a few red grapes up and drop them into my starter, because the white stuff on the skin is the kind of yeast I want for a sourdough starter (alternatively, potato skins) and that these are the kinds of yeast that feed well on sugar (I've heard that a pinch of sugar will get your starter working faster). How much of this is true?