Roseafolia Alternanthera Reineckii

[The Newb]

Afternoon all,

Anyone have any tips on helping aternanthera reineckii along. When I first added it to my new setup a few months ago it grew like there was no tomorrow but lately the new growth has slowed down to a crawl and the majority of the leaves have all folded in on themselves. The other plants (vals, echinodorus, hairgrass etc) are all growing like mad and I still get lots of hairgrass leading me to believe that the nutrients are there but it just isn't using them very well. It is still exhibiting some growth, but even the new leaves quickly fold up and slow right down.

Any help would be appreciated.

Here are the specs. I will try to get some photos up soon.

55gal breeder.
2 x 96W power compact. 1 10k, 1 6500K bulb. 10-12hrs a day.
Recently switched to pressurized co2, usually around 15-30ppm.
Dosing 3/16tsp KNO3, and a little under 1/8 tsp K2SO4, and  KH2PO4 three times a week.
Eco complete substrate with gravel top layer
Water Temperature:76 degrees Farenheit, substrate slightly warmer

[Toss]

IMHO it looks like the leaves are covered with algae and the plant is unable to perform photosynthesis thus slowing the growth.

[The Newb]

An update for any who were wondering, the Alternanthera has started to fight its way back. Thanks Charlie for pointing me towards a possible CO2 shortage. I monitored my CO2 levels more closely for a while and realized I was only getting up to significant levels fairly late in the day. After this I tried pumping more gas in but found I needed an insane bubble count to get the levels up in a more reasonable amount of time. I'm not sure if my disspersion method isn't working that well or if the other plants are just sucking it all up too fast. Since then I have been running just one 96W bulb most of the time with the other kicking in for a couple hours for a mid-day burst. With the decreased light, my CO2 system can keep up better and the Alternanthera has been responding reasonably well. With any luck it will be back to its full glory in a couple of weeks.