converting my 20g

[smomus]

So last night when i got home from work my refractometer was here! Altho I'm not happy with the shipping. The original box got wet (not sure if it was the calibration solution or something else) and was compromised. It was then shoved into another USPS box and sent on to me. Anyone ever seen wet packing peanuts? Nasty! Everything seems to be alright though.
Anyway, I have a 20g fw that I want to start to slowly convert to brackish and eventually marine. I know I need to raise the sg .002/week. As far as the refractometer goes, it starts at 1.000. My thought is that i can calibrate the tank water at 1.000 then it can measure the .002 raise in sg. Does any one have a reason why I can't to this?
I am lost as to figure out how much salt to add each week..? Is there some kind of example of how to do this?
Any help is appreciated!

 

[smomus]

In googling I've read that 2 teaspoons/gallon will raise the sg .002.
So my 20g I will add
2 teaspoons * 20g = 40 teaspoons
Basically that is one cup minus 2.5 tablespoons
Does this sound right?

 

[smomus]

This is what I found..

1 tablespoon per gallon = .003 raise
1 teaspoon per gallon = .001 raise

So, assuming you want .002 per weekly water change... tank size * 2 teaspoons = total salt to add

i.e. in my 46 gallon from fresh to 1.002 (change 46 to whatever your tank size actually is) 46 * 2 = 92 teaspoons = 1.9 cups (48 teaspoons per cup)

from 1.002 to 1.004 with 40% water change replace current + raise by .002
.4 * 46 * 2 + 46 * 2 = 128.8 teaspoons = 2.68 cups

from 1.004 to 1.006 with 40% water change .4 * 46 * 4 + 46 *2 = 165.6 teaspoons = 3.45 cups