try to find a easy way to remove nitrate

[some_1s]

just something to share ,by helping my friend to find a easy way to remove nitrate ,as he is just lazy to fine tune his Coil Denitrator as a result it get choke .so as try to help him find a better n easy , i've shut down my Coil Denitrator for 3 day and try to use my Biosand filter to test whether can it remove nitrate n i found out yes it can but at same time it also create ammonia and nitrite .for right now it is running @ 5sec 1 drop .previously it running full load whice i have test and the result is the same with my tank . for 2 week water have not change .normally i change water about 2wk to 1mth

water from Biosand filter



water from tank