ok, try this. you have your KI in the mixing container. put enough water in so that the crystals are barely covered. shake well. then look at what settles out and put a little more water in. shake it up again. you should still have crystals in it but not as much. use that experience to judge the amount of water you put in next.
if you dont have your container marked at the 125ml level then you have to keep doing that add and mix thing until there is just a little bit of KI left undissolved. let it warm up and most of that should disappear as well. if your crystals disappear at any time then stop. you have possibly put too much water in but you are close enough for your purposes if you have been careful. a few stray crystals in the bottom wou ensure exact SSKI .
i do it both ways, both by adding water a little at a time and by having my container marked at the proper level of the solution i am making. this is also a triple check on the type and purity of the crystals i have. it always works that when its warmed up and i add that last little bit of water up to the mark, bingo! the crystals have all disappeared and the the solution is right at the mark on the bottle. perfect SSKI every time.
and if THAT dont do it...
put water in the crystals as above and shake it and let it warm up and then decant the liquid off leaving the remaining crystals. what you decant off is real SSKI . then judge how much more to add tot he crystals without dissolving them all and do that again. if no crystals remain after adding water then whats left in there is watered down somewhat and you can use that as you see fit.
the fact is that your dose is not that important. the big importance is to be taking enough. if you think you made a thin SSKI then adjust with a couple of extra drops. no biggy unless you are keeping track for research purposes.
a friend of mine doesnt screw with any of this. he takes a liter bottle and puts 333grams in that and fills the bottle with water. that gives him one third strength and he can simply triple the drops to count dose. also, for some reason, the crust that forms at the mouth of the bottle bothers him. to me its a sign of complete saturation.
this really isnt hard, its just new to you. be bold.