Mine looked exactly like yours a few weeks ago. Start dosing excel mine was gone within a weeks time. I have decided that I am going to dose excel for good now. I bought the generic stuff from dealmed.com let me know if you want the link and I will look it up for you.
Also as far as dosing goes Tom Barr recommended I start dosing my micros more often. He said it would make the c parva grow more upright. I can't tell you how right he was. It has been less then a week and I have already seen more new leaves then I have ever seen also all of them are growing upright. I use millers microplex myself. I just dry dose it however on a tank as small as yours you would have to mix up a batch.