One of the most popular questions we get is, "How do I make my water brackish?" So here is the way that I mix water, what you will need, and the formula I use to figure out what SG water to add to get your desired result.
First things first, remember, only raise your SG by .002 or less per week, even on the first increase, or you will kill your bio filter that you just worked so hard to establish.
I'll start from scratch, like you you know nothing about brackish water, and describe the process:
Things you'll need:
1) Container at least 3/4 size the total volume of your aquarium.
2) Marine salt
4) A measuring cup, plastic or glass preferably (metal corrodes)
5) Hydrometer or Refractometer (refractometer is more expensive but well worth it)
7) Power head of some sort
1) Fill the container with water equaling 50% of your tank volume
2) Slowly add salt, you have to experiment with how much to add. Each salt manufacturer is different and even then, there is a difference between batches from the same manufacturer.
3) Add heater. Make sure it is one that can be submerged (don't ask how I found this out because I won't tell!)
4) Submerge power head and turn it on (again, read end note of number 3)
5) Make sure all the salt is dissolved in the container. If you see some sitting on the bottom, give it a good stir and check back in a while.
6) Once you do not see any salt in standing on the bottom of the container, let the water mix for a few hours.
7) Check SG and adjust accordingly.
Let the water mix over night to make sure all the salt has dissolved.
9) Do a 50% water change. Replace what you took out with what you mixed and viola' brackish water!
The trick is to not raise things more than .002 per week. So, based on a 50% water change, the SG of the first batch of water you mix should be 1.004. Now the question is what is the next one and how do you figure it out? I use the formula:
a= your current SG
b= what you need your next mix to be
c= your target SG
So if your tank is at 1.002 and you want to raise to 1.004 the equation should look like this: (1.002+b)/2=1.004
I'll let you do the math.....
"Darwin swings...annnnnnd a miss. Boy Jim, Chuck's suffered at the plate tonight. He's 0 for 3 and I'm not sure he's recovered from that shoulder pull a few weeks ago. I'll bet the front office is re-thinking that contract."