Salinity dropping why?

[Aquattro]

Originally Posted by swill

Is it possible that the salt is settling to the bottom.

No, that's not possible. Salt won't settle out. If the testing device is accurate, there is more topoff water going in than evaporating. Which doesn't make a lot of sense unless the tank is half full. Or you have automated topoff that isn't working right.

[lastlight]

Salt will sometimes migrate to areas of lower concentration (Diffusion). To combat this line the rim of your tank with something saltier than the tank's water. This will effectively contain your salinity.

I'd recommend a MFF or McDonald's Fry Fence.