Water Change question

[andsoitgoes]

I've made up some water a few weeks ago, but with my girls being sick and then just not being able to get the time needed to do it properly, it's been sitting - I've added Liquid Reactor (it's in a 20g garbage can) last week and am keeping it topped up to hold the salinity.

I know that no matter what, some of the good stuff will have percipitated off, but will there be enough good left to use it for a water change? It's been circulating nicely with a couple of power heads... I just don't want to have to drain an entire 20g can and start from scratch if I can help it.

Thanks!!

Nick