Re: General chemistry question about Prime.
Thank you for your questions and for being such a loyal Seachem customer! Because Prime is so concentrated, it really only takes a very minute amount to completely condition your tap water. Since you are treating only your replacement water, which is roughly 20L, or 5 gallons, per bucket, then by my calculations, you will want to add 0.5mL of Prime to each bucket. Suggested dose is 5mL per 50 gallons; 50 gallons/5 gallons=10; 5mL/10=0.5mL to each 5-gallon bucket.
This dose will remove chloramines immediately from your tap water. It does so by breaking the bonds between the nitrogen and chloride atoms (chloramine is NCl3). When these bonds are broken, however, hydrogen atoms will want to bind to the remaining nitrogen atom, thus forming ammonia, or NH3. Most water conditioners stop after this step, leaving ammonia behind. Prime, however, will also immediately work to remove any residual ammonia.
To try and answer your questions more directly, I think you should add slightly more Prime than what you have been dosing (again, 0.5mL per 20L of water). Prime will have already worked to remove chloramines and ammonia from your water by the time you are ready to add the water to your aquarium. There is really no need to mix the water, as simply walking from the faucet to the tank will allow the Prime to circulate throughout the bucket sufficiently. We sincerely hope that this information helps and that you continue to be satisfied with Prime!