There has been a drastic change in the water in my 29 gallon tank and losing a fish a week for the past 3 or 4 weeks. My water conditions were ideal up til a couple weeks ago. Now my nitrate is way out of wack and I can't get my PH and Alkalinity up no matter what treatment up! I have tried every treatment I could think of. I have not added or taken anything out. I have had this tank set up since July. My other water stats including Amonia is ideal. What is going on here???