Ok my starter is doing great but now I need more. To increase the amount of starter I maintain can I just feed with equal weight of flour and water without discarding any? I have approx 2 cups of starter I want to keep 3-4 cups on hand. a typical feeding involves removing 1 cup of starter then adding 125-130 grams of flour and equal weight of water. Should I just add the 125 gr of ea the next time I feed without removing any?
'Used' flour is a dead weight (literally and figuratively), in my experience. If I need more starter, I will usually just remove the excess, and add more flour/water.
Of course you may do just as you suggest. However I find that I need to store only a small amount, keeping that in the refrigerator. When I want to make bread I remove it from the refrigerator and build in two steps allowing about 8 to 12 hours of fermentation (at room temperature, 70 to 85°F) in between feedings. The starter is ready to go then. I also keep a small amount of dried starter in a plastic bag in the case of disaster.
Ford
You should realize that if you keep more starter, you have to feed proportionally it more. If you feed one cup of starter using 125 g of flour and 125 g of water, then you should feed two cups of starter with 250 g of flour and 250 g of water.
If you do what you're suggesting, you would be underfeeding the starter a bit. Doing it once isn't a big deal, but if you underfeed on an ongoing basis, you may see changes to the starter you don't like.
Do you really need to maintain 3 to 4 cups of starter? Unless you're keeping the starter at room temperature and baking daily so that you constantly need a good supply of active starter, you'll probably end up finding you're wasting a lot of flour maintaining so much starter. It's easy enough to build up the amount you need when you need it.
A quick and speedy method to refresh your starter without discarding part of your starter: take your starter out of refrigerator. Divide the starter into 2 separate bowls. Add the amount of flour and water that you calculate you need to each bowl. Stir, cover. Let each bowl sit at room temp for 6 to 12 hours, until double in volume.
Tanga