The entire metric system was based on the physical properties of Pure water.. Water freezes at 0 celcius and boils at 100. 1 ml of h2o weighs a gram and 1cubic millimeter=1ml=i gram and so on. But this only works for pure h2o. Other substances have different densities which throw off the whole lineal relationship as in the salt in salt water. 8)
FILSTAR Pimp #2
75 gal heavily planted,50/50 Black beauty,Eco-complete substrate, Pressurised CO2 with solenoid, ph controller, AB Reactor 1000, 330 watts 9325K GE PC lighting,Ehiem Liquidoser, 2-Filstar xp3 canisters.