I am having a big nitrate problem. I tested my 20 gallon tank a week ago and nitrate levels were very high so i performed a 25% water change. 2 days ago i tested again and they were still high, so i did another 25% water change and added Tetra EasyBalance, because of the nitrabin it contains. Yesterday, they were still high (around 100ppm) so i performed another 25% water change and vaccumed all the debris from the gravel. I also replaced the carbon part of my filter and added Cycle. Today i'm going to start doing daily 10% water changes, instead of 25%. Could something be wrong with my test strips?? Why is my nitrate still so high??