The Puffer Forum

I've begun bringing up my freshwater tank with my GSP to a brackish tank. I bought a bag of Instant Ocean and added 1 1/3 cup of salt to my 30 gallon aquarium, which according to my calculations should raise the SG to 1.002. This is going on the basis that 1/2 cup of Instant Ocean will raise 1 gallon to 1.022. But I'd like to get a double-check on that from people who've done it before.

If my math is right, then my schedule will look something like this ...

2nd week
Add 1 1/3 cup of Instant Ocean to raise the salinity to 1.004
Do 6 gallon water change, using 1/2 cup of Instant Ocean for SG 1.004

3rd Week
Add 1 1/3 cup of Instant Ocean to raise the salinity to 1.006
Do 6 gallon water change, using 3/4 cup of Instant Ocean for SG 1.006

4th Week
Add 1 1/3 cup of Instant Ocean to raise the salinity to 1.008
Do 6 gallon water change, using 1 cup of Instant Ocean for SG 1.006

And so on, until ...

8th Week
Add 1 1/3 cup of Instant Ocean to raise the salinity to 1.016
Do 6 gallon water change, using 2 cups of Instant Ocean for SG 1.016

This is all on the basis that 1/2 cup of Instant Ocean makes 1 gallon 1.022, so presumably 1/2 cup makes 11 gallons 1.002. Is this correct? Anybody want to double-check me?

You need to measure with a hydrometer or refractometer to be sure. That was a very rough estimate & it varys greatly with salt brands & density.

Or you can play it safe and add a smaller measurement each time until you get a hydrometer or refractometer.

Make sure you dissolve it in water first too, don't just dump the salt into the tank.

What was a rough estimate? It all seemed pretty precise to me. I didn't just assume that's what the salinity would be, that's what it said in the instructions. And of course I'm dissolving it before putting it in the tank.

People say in all these forums and articles "bring the salinity up slowly." But they don't say how to do that, because knowing how much salt to add is pretty crucial. Is raising it .002 a week really that big a change?

It's OK to raisze .002, if you are sure that is how much you are raising it, by measuring. It doesn't huret to do slower though. Where did you read that this was a precise amount of salt?

I'm not sure what you mean. I read on the box of Instant Ocean that 1/2 cup of salt raises the SG of 1 gallon of water to 1.022, so 1 1/3 cup ought to raise 30 gallons by .002. All I'm asking is if my math is correct, since this is the first time I've tried to do this.

Your math is correct but there are times that it will not be exact. You must always check by measuring the resulting SG. Every time you expose the salt to air (moisture), it gets denser.

Don't forget to top the tank off with unsalted declor water before doing the water changes. Water evaporates but salt doesn't and it will condense in the tank, raising the salinity.

Yes, I know that. I've kept a saltwater tank before, but not a brackish tank, nor have I tried to change a FW to brackish before. There's so little information about the process of changing it over.

If you've kept a marine tank then converting a FW to brackish should be a walk in the park. You don't have a hydrometer or refractometer?

Personally, I would go get one otherwise you should stop fooling around with the health of your fish & bacteria and be responsible, no?

Best brackish information I know of: http://homepage.mac.com/nmonks/aquaria/aquaria.html

I do have a hydrometer. I just realized last night that it starts at 1.010. I'll get a new one sometime this weekend. I'm just looking to see if what I'm doing sounds like what everyone else does.

Dan06 wrote:Personally, I would go get one otherwise you should stop fooling around with the health of your fish & bacteria and be responsible, no?

What is this about? I've only just begun the process at all. I've done a lot of research, found a lot of conflicting or incomplete information, I've started the process of changing my tank in what I believed (based on research) was a slow and reserved method, and I'm talking on forums to double-check myself and my math. What in that makes you think I'm being irresponsible? I'd like a logical explanation, please.

Your original post has no mention of what measuring tool you used. I'm just looking out for the health of your fish. Sue me.

That's my logical explanation. Your welcome.

I experimented in a bucket, with 5 gallons of water to determine how much Instant Ocean it would take to raise salinity.

I don't see the need for sarcasm or hostility here. Mommyfox is just doing research and looking for information. Which is to be commended IMO.

FYI, mommyfox, the link I posted above has some very handy calculators in the software section, including a brack calc.