thanks creep for the comment.... other comment are welcomed too!!

Will wait for a week to see if they starts to growth.... hopefully...
[I am not sure whether they will can last till then as the melting seems pretty 'teruk'. Also, my naughty suck-mouth fishes keep sucking them in searching for food pallet which dropped in between the melting riccia.... ]

My tank is pretty small @ 40cmX23cmX22cm @ 5.34 gallon. I will twist the arm of my PLC(I have total of 22W from two PLC-one 9W and one 13W) to closer to the water surface so that more light will 'go into' the water to reach the riccia at the bottom. However, that will make the daily clean up harder as I am using a cup to scoop up the protein layer on the surface everyday currently(and top up some water after that)....

humm... long waiting for my riccia to growth......