I have been running a 29 gallon tank for over a year now. Last week I was gone for 3 days at my finace's house and returned to find my aquarium water very green and opaque. I immediately changed a 3rd of the water along with the filter and added some drops to clear the water. The next day, the water was clear but my ammonia and nitrite levels tested very high and the ph was all off (tested 5.0). I changed 1/3 of the water again and let it go for another day. The next day, the test results were the same so I changed 1/3 of the water again and retested the next day. The nitrite level has gone back to 0, but the ammonia is still dangerously high and the ph is still testing 5. In the past 5 days I have lost 2 green barbs and 2 tiger barbs, leaving me with one long-fin rosy barb, one tiger barb, a pleco, and 2 clown loaches. Can anything be done to get the ammonia level down or will I have to keep making partial water changes every day and endure another nitrite spike when it does go down? Also, would it be a good idea at this point to get something to raise the ph level back to 7 or should I wait until the ammonia/nitrite cycle has completed?