I used a cup of water with a teaspoon of hydrogen peroxide (3%). I usually get total germination within 24-36 hrs.
People underestimate the importance of a clean working environment. I keep
everything clean during germination and cloning. It could mean the difference between a successful operation and a bummer.
Also what is the temperature at the cubes? I know your ambient temperatures looked good, but are the cubes themselves getting warm enough?