Clay balls

  • Hello,
    I'm thinking to use the clay balls to enrich my gravel substrate. I don't have any other substrate below the gravel (I received the aquarium from another person already running and cycled).
    I have 3 questions regarding the clay balls:

    - If I place on clay ball per plant in the gravel (so if i have 20 planted plants I would need 20 balls placed inside the gravel) is that as "real substrate" ?If not as good, is it a convenient alternative, which can avoid me inserting a "real substrate" in the aquarium ?

    - In DRAK site, it is said not to place more than 3 or 4 clay balls in a 100L aquarium, but how do I do that id I have 20 plants in a 100 L aquarium ?

    - After 6 months what do I do with the balls that are inside the aquarium ? Should I leave them there, and just add new balls,m or should try to remove the old balls, and in this last case how to do it, once the clay after 6 months should be very soft and not easy to take out.

    Thanks and best regards

  • Hi Luis,

    the Terrdrakon NPK clay balls cotain some grains of NPK-fertilizer (nitrogen (N), phosphorus (P), and potassium (K)). The clay usually keeps the nutrients inside the ball since since there is no/very little flow of water through the clay. The roots of the plants penetrate the clay and gain access to the nutrients.

    However, if the balls are broken open (perhaps by accident when cleaning the soil) the fertilizer grains dissolve. Now, if you have to many grains dissolving at the same time, phosphat, nitrate and potassium concentrations in the water might reach a level, where there could be some problems (for example algae growth or sickness of the fish due to high nitrate concentrations). To prevent these problems, one should limit the amount of fresh clay balls in the tank.

    The balls contain enough fertilizer to support more than on plant at a time. I once had a big Echinodorus osiris (about 25 leaves, each about 7 cm broad and 35 cm long) and a Echinodorus amazonicus (just a little bit smaller than the E. osiris) in a tank. They were planted 40 to 50 cm apart and I put one NPK-clay ball in the middle between the plants. Both plants penetrated the ball with their roots and grew very well. So you can see that even big plants don't necessarily need one clay ball for themselves.

    If you have plants with big root "networks" (for example all big Echinodorus plants), you can put a ball close to them. Plants with small roots in the soil (Hygrophila polysperma, Rotala rotundifolia, Carolina cabomba, ...) usually absorb nutrients with their leaves and don't need an extra clay ball in the soil.

    After six month, the balls will be very soft and slimy, but they still stick together so you can take them out easily if you want. However it is not necessary to take them out, since they do no harm in the soil! If the balls are penetrated with roots, one should not take them out, because you would damage the roots.

    Does it replace a substrate? Hm, tough question. The clay balls offer the big advantage that you can give NPK-nutrients directly to the roots without over-fertilizing the water. I used quartz gravel with clay balls and as described above, my experiences with the NPK clay balls are very good.

    Best regards, Volker