salinity question help

[emilsanto]

i use red sea brand salt and i have a reading using a hydrometer
or 1.020 to 1.021 at 81 degrease. thats were the instruction that came with the salt say it sould read. my question is.
is this ok ,,will the sality go up at lower temps. is there a way to tell what my true salt levels are. also should i put more salt in ?
i just dont know. if its at the above reading know does that mean that it would be right on at say 78 degrese. can anyone help me
thanks

[Jerry W]

The numbers you're giving are for specific gravity(SG), not salinity. Personally, I'd invest in a good refractometer. Most hydrometers are not very accurate. Shoot for a salinity of 35 ppt. SG readings will vary depending on the temperature. You want to look at the actual salinity, and not SG.

[emilsanto]

ok do you know what the sg should be at 81 degrease
thanks

[collins]

Jerry W is right. You should just spend the money for a temperature compensated refractometer. They are not that expensive.

If you don't, you will need to find someone who has one and calibrate your hydrometer with it and then, if you have the plastic swing arm type, ensure that there are no air bubbles on the arm.