Why do brown stains form on the bottom after inserting JBL Manado Dark?
JBL Manado Dark is a natural product. This may initially lead to a slightly increased iron content and raised hardness values, which will normalise in the course of several water changes. In soft water a harmless iron efflorescence can occur. Rinse JBL Manado Dark briefly with tap water before use to remove any abrasion rubbed off during transport.
If iron flowers (flos ferri) occur, you can rest assured. There is no danger for your invertebrates and fish. Plants absorb iron through their roots. You can siphon the iron flowers with a fine air hose, stir them into the soil and change 50% of the water every 2nd day for the first 10 days. This reduces the effect.