Potassium is required in a small number of plants used as a catalyst, especially in the conversion of proteins and amino acids, but the biggest concentration of potassium is contained in seaweed. Potassium deficiency can lead to impaired photosynthesis and increased respiration, resulting in stunted growth and fragility of the plants so easily broken and damaged (Dwidjosaputro, 1992).
Potassium also can activate some enzymes work, and is the most important component in the fluid osmotic adjustment mechanism in the cell, and directly influence the spring rate of membrane permeability and phosphorylase in chloroplasts (Agustina, 2004). The content of potassium in the sea around 380 mg / L (Subandriyo, 1996).
Figure 13. Utilization of nutrients in the water
The existence of ecosystems around the diatom seaweeds can disrupt biological organism’s life, especially when the seaweed on the stadia microalgae. At this stage of diatoms can take even enter the cell seaweed, whereas when the seaweed in the adult stage (microalgae), diatomaceous stick and live as parasites on the seaweed thallus alongside other epiphytic plants. The minimum requirement would diatomaceous silicate for growth is 0.5 mg / l.