## 5 Discussion  
Standard aquaponics and vermiponics systems were designed, built and used to assess the impact of water replenishment and earthworm presence on plant and fish growth and the overall productivity of each system. The results proved that water replenishment effectively improves plants and fish growth and the productivity of the aquaponics with and without the presence of earthworms in the growbed. Further improvement of the performance was observed with the vermiponics system. The results are in agreement with the literature that suggests earthworm presence enhances the nutrient availability of plants in the aquaponics [21] and thereby improves the growth of the plants. Similarly, it is reported that the earthworms help to increase the crop yield and root structure of the plants [22]. Earthworms in the aquaponics growbed could improve the biofililtration mechanism and support to mineralize nutrients, influencing the bacterial ecosystem [23]. In both terms of experimentation of this project, it was evident that the vermiponics testbed yielded better productivity than the standard testbed because of the worm's presence. It is quite evident from the data presented and the images of the vermiponics testbed that it showed a better yield compared to the standard testbed.  
Results show that a better yield close to 3% was possible with regular water replenishment of 19 L in a 100-liter fishtank for the standard testbed and a more than 5.5% productivity was possible on the vermiponics system yield. Leaf breadth size showed a slightly better productivity in the standard testbed than the vermiponics system after replenishment. Leaf length and stem size were the two attributes which were highly impacted by water replenishment according to the results. Plant lengths increased faster with the replenishment term than the previous term of growth without replenishment. Fish length and weight increased steadily. The stems of the plants looked stronger, and the leaves were greener and healthier when replenishment was applied. It is also noted that the fish were more active and looked healthier during replenishment. When the water quality parameter values were collected from the fishtank water while no replenishment was applied, pH values were found to drop over time, making the fish water more acidic. Without replenishment, the Total Ammonia Nitrogen (TAN) values were increased from 0  
Figure 11: General comparison between standard and vermiponics testbed before and after water replenishment against the productivity score.  
to 1, which is detrimental for fish life [10]. Water temperature showed an increase up to 2 degrees when no replenishment was applied. Dissolved oxygen values dropped over time while turbidity was unaffected. Water replenishment helped the key water quality parameter values to stay optimal. That is, pH and DO values, which dropped when no replenishment was applied, maintained the optimal range throughout the replenishment term. TAN values were at 0 after replenishment. Turbidity values remained unaffected during replenishment. The literature shows that most of the comparative studies have been performed using manual approaches, whereas this project effectively blended the use of technology along with conventional methods.