Converting gsp to brackish.Math help,please

[Noddy]

Hey, there.
I currently bought 2 small gsp's and want to convert them to brackish.
I read all the info available, but still can't figure out the math.
Say i have a 40Gl and i want to increase the salinity with .002 a week, and i take out 10Gl of water to replace with salt water, how should the saliniy be in the 10 new Gallons to raise the whole 40Gl with.002?
And will i do .002 in one waterchange or do i do several smaller waterchanges?
I hope someone can explain this to me.
If i missed a thread on the subject, a link will do too.

 

[fishtex]

I would highly recommend buying a hydrometer or refractometer so that you can test your salinity accurately. Don't worry about raising the salinity quickly. Take your time and do it slowly. I would mix 10 gallons to about 1.005 for the first waterchange. then start upping it slowly from there.

 

[Noddy]

Sure, i'll get the meter too, but couldn't figure out the ammount i needed to go slow on my fiter.
Thanx for the advice

 

[Pufferpunk]

http://www.**************.com/forum/viewtopic.php?f=5&t=19348

 

[fishtex]

yeah the standard seems to be no more than .002 per week, I've never tried to go that fast though.

 

[Noddy]

http://www.**************.com/forum/viewtopic.php?f=5&t=19348

Thanx for that link, that's the math i was looking for!

 

[Pufferpunk]

Lots of great info at that site!