How To Achieve The Appropriate Salinity For Bumble Bee Gobies?

[TooManyChoices]

I just set up a tank for some bumble bee's and am wondering how much salt I should add.
 
The tank is roughly 10 gallons. I'll be using unionised, evaporated sea salt (the stuff like little rocks).
 
How much should I add? One tablespoon per 5 gallons? Two tablespoons per 5 gallons?
 
I don't have a hydrometer or refractometer so it'll be a bit of an inexact science. 
 
Any ideas?

 

[Paradise3]

Depends which species you're getting - Brachygobius Doriae can live in freshwater. I know because I've had one in freshwater for the past year and a bit and he's healthy as can be. He did recently go on a murder spree and take a chunk out of my female shadow catfish then eat a fully grown male guppy though so whatever you keep him with, make sure it cannot be grabbed and eaten. There are loads of different Species called "Bumble Bee Goby". Brachygobius Nunus, Brachygobius Xanthozona, Brachygobius Doriae, Brachygobius Xanthomelas, Brachygobius Aggregatus. Out of these there's approx 2-3 "freshwater" ones that can live in freshwater but may prefer brackish. As I've said, my Doriae has lived in freshwater for over a year and if quite happy in himself. 

 

[iliveinazoo]

What is unionised evaporated sea salt?

If you were using a marine salt like red sea or instant ocean then 2-3 tablespoons per 10 litres that you add will be fine.

I should say that a hydrometer is cheap and worth it for that peace of mind

 

[Livewire88]

Use a Refractometer.

 

[TooManyChoices]

Thanks for the responses
 

If you were using a marine salt like red sea or instant ocean then 2-3 tablespoons per 10 litres that you add will be fin

 
I might just pick up a cheap bag of it (I think my lfs has a no name brand for about $6.
 

I should say that a hydrometer is cheap and worth it for that peace of mind 

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I'll try to pick one up, as I will probably need it. 
 
Just have to save a bit of money first!