Aquarium vs marine salt

[fishb0ne]

Can anyone tell me what the difference is? I'm trying to determine which will be better and I know it depends on the application.
I've got some API Aquarium Salt which is made of, I quote

All natural salt, made from evaporated sea water

Doesn't that mean it's very close, if not the same, to marine salt?
I've also got a big bag of Marineland Instant Ocean marine salt which I use for my brackish biotope.

Here's where I'm at. I have a 5.5 gallon tank with 1 dalmatian molly, 1 wagtail platty and 1 rainbow guppy and also 5 ghost shrimp. From what I can tell all these critters benefit from a bit of salt in the aquarium, especially so the shrimp which need a bit of iodine for healthy moulting.

Which type of salt should I use? Are 2 tbsp too much for 5.5 gallons?

 

[coldmachineUK]

Aquarium salt would be fine for your 5.5G tank with the molly, platy and guppy. Livebearers do benefit from the addition of a little pure NaCl (i.e. aquarium salt).

Marine salt contains many more elements (from magnesium to calcium) and also helps buffer pH. Since the livestock in your 5.5G don't require these things then aquarium salt is fine.

Brackish biotopes, as you obviously know, do on the other hand, and that's why they need marine salt.

 

[Marc118]

I was under the impression molly's were in fact BW fish. So it would seem they would benefit from marine salt ( actually they can live in SW no problem ).

 

[coldmachineUK]

Acc. to Neale Monks, an expert on brackish fish, mollies are in fact 100% FW in the wild. They merely do better in brackish in home aquaria.
But, he could be wrong I guess!

 

[hc8719]

mollies are often found in brackish enviroments, and while they can live in salt water for sometime, upon being gradually introduced, they cannot live a normal life span in it

 

[fishb0ne]

Marc, I've also heard the same but upon further research I came across the same info as coldmachineUK. They may be found in BW but they're fine in FW as long as you add a bit of salt in them. I'm also pretty confident that what I purchased was not wild caught, but bred in captivity.
And yes, I know that for my brackish to not use anything but marine salt.

Now that I think about it, 2 tablespoons may be a bit much because although the tank is 5.5 gallons, realistically speaking it's holding about 4.something gallons of water. Or maybe I can go 2tbsp since all the critters in my aquarium can tolerate it just fine.

 

[maxwell1295]

I prefer to use kosher salt instead of regular aquarium salt. It contains a lot more minerals without the buffering effect.