adding calcium - 1/3 of the appropriate doze per addition?

[nikon5400]

My hth bottles say "if large amount of calcium increaser hardness is required (an increase of more than 50ppm) add 1/3 of the appropriate doze per addition. Wait 4-6 hours between additions"

My clorox and aqua chem says "Divide total dosage into thirds. Add 1/3 at a time, waiting 6 hours between additions.

Why 1/3 at a time? Does it have anything to do with filter pressure or stains on the pump lid?

Why hth mentions 50ppm, while the other two don't?
If I need 50ppm and use hth, I can do it all in one shot but if I need to add 75 I should do 1/3 at a time??

Thanks

 

[mknauss]

It is best to add calcium chloride in small batches so you can be sure you get it fully dissolved when you broadcast it in the deep end. Brush well.

 

[nikon5400]

It is best to add calcium chloride in small batches so you can be sure you get it fully dissolved when you broadcast it in the deep end. Brush well.

what is a small batch?

I needed about 50ppm and went with hth. 3 bottles, 6 additions (diluted with water before adding to the pool) but only 5-10 minutes apart. Only then I looked at instructions on other bottles (other brands), which don't mention 50ppm.
I brushed after each addition, didn't see anything on the pool floor

 

[mknauss]

2 or 3 lbs at a time. More if the water is warm and it dissolves fast.

Be careful dissolving in a bucket. Exothermic reaction.