Rubidium is a trace element present in seawater of reefs all around the world.
Rubidium is a trace element that is not yet fully understood but kept around 200 µg/l has been shown to have positive impacts on coral colouration.
Naturally, Rubidium in seawater varies but its concentration are generally between 180-200 µg/l.
1 ml of Reef Zlements Rubidium increases the concentration of Rubidium in 100 litres of water by 5 g/l.