oops wuv must have added that as I was composing...I forgot that was in there. Oh well, for what it's worth...
I use 2 litre soda bottle also... First I decapsulate the eggs. This eliminates the shells on the eggs which have been said to cause swim bladder, also kills bacteria and increases hatch rates.
#1) 1/2 tsp eggs in a small cup(old petsmart betta cup) with two inches water, I let that soak for a min of 1 hour, or usually overnight to rehydrate the eggs.
#2) add 1 inch more of bleach and let sit for approx. 4 min until eggs are reddish color of newly hatched shrimp. too long and you scramble the eggs.
#3) strain eggs using coffee filter and rinse with clean h2o.
#4) fill cup 3/4 of the way full with water and add eggs back. then add enough dechlor for 1-5 gallons of water to cup ( a little extra never hurts). agitate gently with spoon for a few min.
My hatchery looks like this
I have 2 or 3 set up almost always so i have a continuos fresh supply. The bags on top act as cheap splash guards and I keep my tubes clothespinned up to prevented unwanted flows when I unplug from my valve.
and I have them on a valve like this
In my hatchery I use
4 cups water
1/8 tsp baking soda (for buffering)
4 tsp salt
1/2 tsp decapsulated eggs
I provide plenty of aeration and light. They get full sun light all day and a dim light at night. Hope this helps some, I will happily answer any questions.