Drop in Salinity

[schulze]

Hi.

I’m working on my first SW tank, and I just encountered something that I found odd. I have had the water in my tank for about 4 days now. The first day I added the salt, my hydrometer read it as > 1.030. After some water changes, I got it down to 1.022 and want to keep it there.

Yesterday I added some base rock, and added carbon to by filter to help clear the water from sand. I also added a tablet to remove chlorine and what not.

Today my hydrometer is reading at < 1.010. (My hydrometer's range is 1.010-1.030). Can anyone explain why the huge drop in salinity?

The tank is a 20 gallon and the only current comes from an Aquaclear 200 filter (my powerhead is in the mail). Also, that is a raw shrimp in the bottom left of the tank, but I doubt that affected anything.

Thanks.

 

[roka64]

WELCOME TO AA!!

Props for you doing a fishless cycle!!!

Is there any chance you can buy a refractometer, to replace the hydro, something like this:
http://www.drsfostersmith.com/Product/Prod_Display.cfm?pcatid=9957&N=2004+113761
They are way more reliable.
I believe the hydrometer is supposed to be about 5 inches below the surface. I also noticed, that if the temp is not within the range the hydro was calibrated at, it will give you off readings. When I did my first batch of SW, it was cold water and I couldn't get a decent reading.
On that note, it is recommended to pre-mix your water (24-48 hours) before adding to your tank. This allows you to match your tank's pH, temp and salinity plus it aerates the water nicely. In your case, you are starting your tank, so, it is not as vital.