Nevertheless, after an hour, all of the nitrate concentrations dropped dramatically to around 0.1-0.15 mg/L. After 2 hours, most of the macrophytes were able to absorb and uptake all of the nitrates to make the concentration of nitrates in the water sample 0 mg/L, which shows that each different macrophyte was effective in filtering out the nitrates. These findings are supported by SEM images taken before and after the filtration process.