Brine shrimp eggs can be viable for a long time, years in fact. They can also go bad. Maybe you have some bad eggs. Maybe not.
For some reason brine shrimp eggs are sensitive to salt concentration and temperature when hatching. So you might need to try a couple of different conditions to hatch the eggs.
Also water in which brine shrimp eggs have hatched seem to catalyze the next hatch. It is probably a bacteria that does this and it probably comes in on the eggs but has to have time to develop in the hatching container. I use the same water to hatch brine shrimp eggs on a daily basis at 74 F which gives me an almost complete hatch in 24 hours. I prepare the salt water for hatching in the following manner. I prepare a saturated salt solution using salt crystals sold in 40 pound bags for deicing sidewalks. In a gallon jar I add about two inches of salt crystals and fill it with water. Stir to get the salt into solution. After a few hours there should still be some crystals on the bottom. The clear liquid on the top contains all the salt that can be dissolved in the water so it is a saturated salt solution: you cannot get any more salt to dissolve into this liquid.
I then add 90 milliliters (about 1/3 cup) of the saturated salt solution and 4 cups of water to the hatching container. Throw in up to a teaspoon full of eggs and add enough air via a stiff air tube to cause the mix to move like it is boiling. 24 hours later I remove the air tube and wait about 20 minutes for the brine shrimp to collect on the bottom and the shells on the top. Then drain out the shrimp from the bottom through a brine shrimp net, rinse lightly with fresh water and place in fresh water for feeding fish.
I just add more eggs for the next hatch.
These are still in use after 10 years. One on the right has a valve on the bottom for draining the brine shrimp.
Adding calcium can help hatch rates, btw. (According to a study I saw.)
Brine shrimp eggs can be viable for a long time, years in fact. They can also go bad. Maybe you have some bad eggs. Maybe not.
For some reason brine shrimp eggs are sensitive to salt concentration and temperature when hatching. So you might need to try a couple of different conditions to hatch the eggs.
Also water in which brine shrimp eggs have hatched seem to catalyze the next hatch. It is probably a bacteria that does this and it probably comes in on the eggs but has to have time to develop in the hatching container. I use the same water to hatch brine shrimp eggs on a daily basis at 74 F which gives me an almost complete hatch in 24 hours. I prepare the salt water for hatching in the following manner. I prepare a saturated salt solution using salt crystals sold in 40 pound bags for deicing sidewalks. In a gallon jar I add about two inches of salt crystals and fill it with water. Stir to get the salt into solution. After a few hours there should still be some crystals on the bottom. The clear liquid on the top contains all the salt that can be dissolved in the water so it is a saturated salt solution: you cannot get any more salt to dissolve into this liquid.
I then add 90 milliliters (about 1/3 cup) of the saturated salt solution and 4 cups of water to the hatching container. Throw in up to a teaspoon full of eggs and add enough air via a stiff air tube to cause the mix to move like it is boiling. 24 hours later I remove the air tube and wait about 20 minutes for the brine shrimp to collect on the bottom and the shells on the top. Then drain out the shrimp from the bottom through a brine shrimp net, rinse lightly with fresh water and place in fresh water for feeding fish.
I just add more eggs for the next hatch.
These are still in use after 10 years. One on the right has a valve on the bottom for draining the brine shrimp.