Only increase the sg by .002 per week so your bacteria colonies dont die. Too much of an increase will shock your system, kill the bacteria consequently you un cycle your tank, creating a massive die off and having an ammonia holocaust. This puffer in the end needs an SG of 1.005 and no more than 1.008. Yes, you read that right, he is LOW END brackish. Get at the least a hydrometer or if you can afford it a refractometer so you increase the salinity accuratley. Agaim, It is imperative you do not go past .002 SG a week for your bacterias sake. You need at least 15g per F8. In a community tank, he will kill your other fish. Its a species only breed. Provide heavy decor with plenty of caves. Any other questions? Ask away