salinity too low in cycling tank


I know that I don't know
I followed all the directions for the Kent Marine reef salt that I am using, but my salinity is too low. It is 1.021 according to the floating hydrometer and the instant ocean one with the arrow arm thing. I also used a pump on it for a day before putting it in the tank.
Should I try to raise it and if so how?
I am going out of town for a few days so over 4 days I will probably have some evaporation during that time.
Oh and BTW, I have ordered a refractometer. It'll be here next week. There is nothing living in the tank other than rock and sand.
I find i always have to use more then the mix states, now i just pour and mix lol. Just top up with saltwater until you hit your desired amount.
Are the refractometers on eBay okay? My parameters are heading in the right direction so if I get the salinity straight I'll be good.
Ammonia .25
Nitrite .50
Nitrates 0
What should my salinity be for fish and coral? I think it is suppose to be higher for coral but why?
The ones from Ebay are fine. Did you get the calibration fluid with it? You will need that to make sure it is calibrated. I think it costs $3 to $5 -- not expensive.

Natural seawater is 1.025 - 1.026. That's what you should shoot for in your tank.