When I mix the 510 pyro I put it in small enough bottles that I can use it up fairly quickly (months). When I get down to the end of the bottle I turn it upside down over the next bottle for a couple hours after making the first batch from the new bottle. What little is left I don't worry about.
Sandy's brew could be handled the same way.
I don't think I'd want to be using a TEA developer out of a two liter bottle.
Was the pump strokes pretty consistent in the amount they delivered with each stroke? If you're getting .5ml per stroke and need 10ml, would the 20 strokes introduce to much variability batch to batch?