3.2.2. Water quality improvement by water spinach floating bed
Part of water quality index of the 600 m length river, including water temperature, pH value, transparency and DO value, are shown in Table 2. The average water temperature was about 30◦C, which was consistent with the environmental temperature. pH value is very important for growth of shrimp. If the pH value in shrimp pond was higher than expected value, it would be regulated to a suitable value by drainage and exchange water. It was shown that pH value was maintained alkalescency during experimental time, and the value in the selected river was almost the same as that of shrimp pond. In addition, it was found that there was no significant change of transparency, which indicated that the water spinach floating bed has little effect on transparency of river. The average value of DO was 3.0 mg/L, which decreased as the water temperature increased.