I purchased a package of hypo clear agent (it is powder), I would like to use small batches of this. The package I purchased has 200g sodium sulfite and 2g sodium bisulfite. According to the instructions it recommends mixing 750ml of warm water(125 degrees F) with sodium sulfite first and desolve and then add the sodium bisulfite next, then add cold water to make a total of 1000ml to create a stock solution. Then it recommends mixing from the stock solution a 1:9 ratio. I have been unable to find anything as to how long this stock solution would last. From what I have found it is recommended that it be mixed and then thrown out. Does anyone have suggestions for mixing smaller batches. Any help is appreciated, as I am new to the chemical mixing.