New member
been reading up on ich and came across a formula...Ive tried to put in my 10min of thinkn and figured someone here could explain this formula to me. It is a formula to show the reduction in salinity over a period of time.

found this info at:


Your starting point should be between 1.025 and 1.027. Replace about one fifth of the volume with RO, RO/DI or aged freshwater that has been well aerated. Repeat this 12, 24 and 36 hours later, monitoring the specific gravity along the way. After the fourth water change the specific gravity should be 1.010 or pretty close. Wait a few hours to make the final adjustment to get down to 1.009. Note that you can estimate the resulting specific gravity. If you are changing one fifth of the water and the current specific gravity is 1.025 the result will be:

((1.025*4)+1.000)/5 = 1.020 approx.

Can someone explain this for me