Nutrient Quesitons

I'm using foxfarms currently on my grow and i've been wondering something. when i prepare a nutreint solution and i use but have leftovers, can i store it somewhere and use it again when it comes time or do you have to throw out whats extra everytime?

I've also noticed recently that when i make a nutreint solution that that ph is pretty low around 6.0 i think maybe less. I don't have any chemicals specificially meant to raise ph for plants but is there any common house hold item that can be used to raise the waters ph without there being a danger of damaging the plant.

If your going to save it you'll want to put an airstone in it and keep it lightproof. I've found that if you let the mixed nutes sit overnight with an airstone in it the ph will rise, they are designed this way it's called ph buffering. Mix in a little unsulfured molasses and it will rise more from the beneficial bacteria bloom. Also Foxfarms has two types of Grow Big nutes, for hydro and for soil they will ph buffer differently.