Looks fantastic Korakot.. I love discus in planted tanks and this will be stunning as it grows over time.. Looking forward to more pics!!
I am not an expert but I buy a whole Ox heart for £5 from the local butcher and its enough to last months and months. I used to buy the pre-made stuff but I too found it almost dissolved when I put it in the tank. When you are feeding juvi discus 4 or 5 times a day it can soon impact the water. I now buy a whole heart and after cutting all the bad bits off it I cut it into smallish 3cm cubes and freeze them. When you want to feed the fish just take one out and rub it down a medium/small sized cheese grater. You wont get any tiny pieces and you if you turn the filter off for two minutes you wont get one single piece uneaten. I do the same with frozen mussels and prawns, although I chop these with a knife. I also mix the feed up with chopped peas, spinach, garlic etc as and when I feel like.
It took the missus a while to accept chunks of beef heart in the freezer though... good job she doesn't see me hacking the huge heart into bits on the kitchen side!
Oh yeah... and If I fail to clean the cheese grater properly... that doesn't go down too well either...haha