I use 2 liter bottles inverted with cap on bottom.
I use rigid airline to make sure the bubbles are at bottom of bottle.No airstone, too much bubbles puts eggs out of water on side of bottle.Just enough air to keep them from settling .
When I harvest I pull the air out ,let the eggs float and shrimp settle and use a separate [ dedicated ] rigid airline to syphon [again from bottom of bottle] into the sieve.
The sieve fits in a small Toms Dip and Pour ,so I reuse my salt water a couple times until it is easy to tell it is not clean..
The easiest part for me is I have a 75 g reef set up so I just use that for my saltwater source..
IMO low hatch rates at e from poor eggs .
If you got them from LFS you would not believe the difference in quality and price from Brine Shrimp direct.