Having trouble with My 1-2 grow alternanthera reineckii mini.it was one of the first plants I put in since the tank was set up .initially I put the lack of growth down to being a new tank and getting used to it's new surroundings.but that was 7 weeks ago.its not done anything in that time.some of the stems wasted away to mush, and ended up falling to bits.any ideas ? Co2 now up and running, dosing TNC , i even put some JBL root tabs in.this it all that is left from a full pot.