Brackish tank

[JefeAquatic]

I am planning to set up a 20 gallon long for a figure 8 puffer with plenty of filtration. This is my first brackish tank and even through hours of research I cannot get the amount of salt for the 20 gallon. Can someone help with this? I have already kept freshwater puffers and want to jump into brackish because I have both freshwater and saltwater. Any assistance would be welcome. Thanks

 

[Ichthys]

35grams per litre makes seawater with an SG of 1.025
The salinity of brackish water tends to be about 1.005 to 1.010, something like that, so 7-14grams per litre.
The salinity of brackish water varies on a daily basis with the tides, and also with variations in the volume of freshwater coming out of the river (heavy rains, wet season/dry season etc) so the salinity doesn’t need to be constant.

Figure 8s can live in freshwater so I wouldn’t worry much about it. As long as there’s Some salt in the water it’s brackish.