However, my fishes got some white spots, although i have been adding copper to my FOT for more than a week, those white spots are still come and go like ghosts. That's why i am thinking of reducing the SG. But i don't know whether the primitive one can give me a safe reading say i want to lower the SG to 1.010.
Any advice on it?
Primitive one is good enough to measure a SG of 1.010. But low SG is not very good in treating white spot disease.