adding supplements to water change h20

[dga]

its states on many supplements (calcium, alkalinity) that it should be disolved in freshwater. in my 20 gallon, i am only adding limewater for top off which is around 60 oz week. i have a canopy with the lighting installed in it so a glass top must be mostly covering the tank to prevent salt splash and creep so ventillating for more evaporation is not possible at this time. although i change the water every 2 weeks, adding the limewater alone wont boost my calcium and alkalinity levels enough. (my magnesium is good) cant i add say ("reef builder") (dry) along with the salt into my water change every 2 weeks? or must it be disolved in freshwater?

 

[Randy Holmes-Farley]

Some additives can be added, but alkalinity, at least more than a tiny bit, likely cannot as it will push the alkalinity far too high and cause precipitation of calcium carbonate in the new salt water. Calcium and magnesium can be boosted a little in it (I do that with my Instant Ocean), unless you use a mix where they are already excessive (like Oceanic).