get yourself a hydrometer to measure salt. most people will recommend a refractometer, as it is far more accurate, but brackish fish like the amount of salt in their environment to fluctuate, so either will do. but dont go by cups or by weight. its rediculously inaccurate. it gets worse as over time salt absorbs moisture from the air, so it gets heavier, and has a lesser amount of salt (as a percentage). so an instrument desighned for the job is a must.
then you need to get marine salt (not aquarium salt) and raise your SG (specific gravity) no more than 0.002 per week. this number regards to the weight of an amount of water + salt.
1 ltr of fresh = 1.000
1ltr of salt water = 1.022+ (regarded as start of marine conditions)
for figure 8 puffers you will want around 1.005 sg. so it should only take 3 weeks to raise the SG with the puffers in. if the tank is empty, just add salt to the tank till it gets to 1.005. mix it thouroughly in a bucket before you add it to the tank though.
if you wanna raise the SG with the puffers in the tank, take out 1/3 of the water in the tank, and mix a batch of water at 1.006. .006/3 = .002
add this to the tank. you should also look up 'Drip Acclimatisation' on google. its a method of adding fish into brackish/ marine aquariums. its also needed if you buy fish online. simply floating the bag and adding the fish in these situations could lead to a dead fish. so its good to know.
welcome to the dark art of the hobby
