Salinity dropping why?
 

I have a 7 gallon fluvial tank with A singel seahorse in it live sand and a couple of fake plants. My salinity seems to drop for some reason. I had mixed the water 1.022 and then checked about a week after putting the seahorse in and it was down to 1.014. Some how the seahorse surveyed. Does anyone know why this is happening and how did my seahorse survive

How much top off water have you replaced in the week?

What are you measuring with?

Should be a calibrated refractometer.

What kind of salinity tester are you using? Before you start to raise the salinity make sure you go slow. Lower salinity is easier on the live stock then when your salinity gets too high and maybe that's why the seahorse is still alive. It's odd that it has dropped that much. Try to get another source to test it before you do some thing drastic.

I guess I should have said that I have 2 other tanks a 300 gal fowlr and a 90 gal reef. The salinity in these tanks are always consistent so I know the meter is not the problem. Is it possible that the salt is settling to the bottom. There is not much flow in the tank just the filter from factory

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.

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.

I personally use the KFC double down, works for a salinity perimeter and nothing beats the angina after eating one.

Unless you have a secret leak there should be no other way for your salinity to drop like that, are you sure your initial measurement was correct?
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Really the only way for your salinity to go down is if you loose water and replenish with freshwater. If there are no leaks in the tank and no major signs of salt creep, I would have to suspect maybe a incorrect initial reading aswell.

To bring the salinity back up slowly you can just replenish evaporated water with mixed saltwater (1.025) over the next few days. With a tank that small you should be checking salinity a little more often till everything stabalizes. Good luck and keep us informed.

Let's see some pics of the 300g fowlr