hairgrass melting/dying?

i bought some eleocharis acicularis (dwarf hairgrass) a week ago at it was lovely and green now a week on the tips seem to be browning and some stems dying off, i seperated them into smaller clumps, i trimmied the brown tips off most of them earlier on today. i presume the tips are going brown because is was grown emersed and now its submerged but it doesnt explain the stems.
its a new tank 10 gallon tank only 30cm high with 2 inches of aquabasin and manado substrate (by jbl)
i have pressure co2 at a bubble every 3 secs which on the coulour chart (measured by 2 or 4 drops of regeant turning either yellow(low ph high co2), green, d.green, l.blue, blue(high ph low co2)) which on the chart is in the middle so dark green which is also a ph of 7.
i used a ro water at a temp of 24/25 c with minerals and i am doing daily doses of ferropol24 and weekly doses of ferropol(again by jbl) with 2 arcadida arcpods oringal tropical 11 watt lights making 2wpg(if you still go by this rule)
any ideas heres as ive been looking on the net but everywhere i look has a different opinion than the other. here are a couple of bad pics if you can see it in them but it might be a struggle.
i know some people say with the right condtions they can grow very fast and become invasive and need medium light others say they grow very slow and need a very high light so i dont know who to believe aha
cheers