I have 22w of light for my 5gallon tank, which come close to ~4w/gallon... maybe my light is "Made in China' PL type, so the spectrum are not dense enough .

I put in JBL Floropol Liq Fert too. I put in 1ml every alternate day as the instruction said 5ml can treat 20litter, but never mention on the dosage frequency. So I assume it is for every week. My tank is about 20litter/5gallon, so I put in 1ml evey alternal day, and 2ml on Sunday after the 10& water change. My DIY CO2 could be a bit tricky.. for the first few days, the bubble rate is good, but after the 5th day, it come to slower, and kind of 'sleep' in the 10th day....Also, I believe my water temp is not cool enough, it stay at around 30c in the afternoon, and 29 during nite time. I think that why my xmas moss turned to brown and die off .

About triming the riccia close to their mat, which means we cut off the young growing tallies, right? Will the old tallies look as green as the young one down near to the mat? When I look at my, those old tallies that close to the mat has a brown yellow color(maybe lack of light), and they are not in a healthy green color. That's why every time when the riccia grow too long, I just cut off the young tallies, and retie them again, and throw the old out away. Some of the old tallies which attached close to the rock(I just mosqito net to tie the riccia to the rock) seems die off too when I cut off the old mat for retie. Am I tie them too tight or what?
Humm.. seems still long way to get a perfect riccia carpet....