Brine Shrimp science experiment

[km2022]

I have done a science project testing how acidity affects the reproduction rate of brine shrimp. I have tabulated my results, but have come across strange data. The weights of the water + brine shrimp have fluctuated and i can't figure out why. How does it fall, because even if they die, they will weigh the same as when the were alive. The water has not evaporated either.

Please can someone help?

Thanks

P.S. I've attached a picture of my table

[EdEarl]

Container A is a mystery.

 

Container B is spot on.

 

Container C differs a little; do you expect them to be exact or is C OK?

 

Is it possible Tank A someone is screwing with you? Is it possible you are getting moisture from the air, differences might occur by having a different salinity in each tank, or a different temperature. You didn't specify any environmental data, so I'm guessing.