Too much nitrates? No wonder my plants are growing strongly rite? :O
I think I need to get some equipments in order to test the no3/no2/ammonia. Do I need to buy 3 separate testers for each type?

I'm using a hang-on filter which contains bio-rings, activated carbon & a sponge. When I chg the 30% water once or fortnightly, I will clean my filter as well by washing using the tap water. Am not sure whether this info is sufficient.

Now my tank is only left with 37, more than 15 have died since I set up my tanks 5 weeks ago. Is there a way to reduce the nitrate in a tank? If not, what could be the other causes of the high dead rate? I was told in another forum to chg 100% of my water as a last resort.