My recipe for seed cracking water.
I like to float my seeds in this solution for a few reasons.

1- It softens the shell, and makes it easier for the seedling to emerge.

2- I know exactly how many sprout vs. not sprouting, and I Know I'm planting live embryos.

3- The solution will sterilize my seeds, and kill any unwanted spores like Dampening off.

Light turns the Peroxide back into safe water. Too strong will burn your roots!

My method:

I use a 1:9 ratio of 3% Hydrogen Peroxide:Water.

I mix 5ml 3% Peroxide to 45ml Water, and store the leftover water in an Amber bottle for next time.

I float the seeds for a couple days, under low light (like 5000 LUX[88-120 PAR]) until I see tails, and then I immediately transplant in clean coco or soil, or cube, etc.