is your calcium
also the best way to add it imo
is to start with lets say a milk jug add 1 tsp mix it and let it sit over night !! siphon out the clearish liquid out leaving the powder at the bottom and the crust on top !! test first say you ca
is reading 350 !! add your kalk
after your light are out by a slow drip to top off the tank from evaporation !! now here were i do things different with out any issues so far !! but depends what size tank ya have ect.. im dosing around 200 gallons of water mind you !! but i use a reg airline tube and just siphon the water into my fuge !! dripping would be better for smaller tanks for sure but in my case an air line sypon works just great
other wise just put a knot at the end of the airline to slow it down
the next day at the same time ya tested the day before test ya ca
again !! now lets say your readings are 400 !! then ya know ya need to add a bit more kalk
so next night try adding 1 1/2 tps and see where it leads ya !! every tank is different due to what corals ect ya have using ca
ya know !! but 450 is your target range !!
as for iodine/strontium most dont and they do their reg water changes will keep up with that !! i myself add iodine due to the many crabs/shrimp i have and everyother day i would add 2 drops of loguls and when i test for it it never shows on the test but every time i add it someone molts so i feel its doing good !! but if ya dont test for it dont add it !!