Op you may find it easier or more convenient to do the ClearRez recipe. Some people are intimidated by dosing straight shock into their mix but i assure you its legit and it works great, especially if you regularly combat high water temps.
Caveat: the smaller the volume of water you are dosing, the more accurate you should be. Smaller variations affect smaller volumes more significantly. Conversely, the more water volume you have, the more wiggle room you have on your dose, because a small variation will affect it less. Always thoroughly dissolve the shock in water before adding it to your mix, i recommend using warm water to help dissolve faster.
That being said, the plants can tolerate a slightly higher dosage without ill effects if it isnt sustained. Remember also that free chlorine also evaporates out of the solution over a fairly short period of time so after a day or so theres no free chlorine anymore anyway. Now the chlorine that ends up reacting with organic materials is still in there however and is no longer doing anything positive, and if its a lot or it accumulates it can end up screwing with your chemistry. If you are only treating a bad root rot problem you may want to flush your system after a day or so but if you use this as a regular preventative measure it should be minimal.