After being abscent from tropical fish for 10 years, I set up one of my 150g tanks 72x24wx18h. Using regular aquarium gravel, I planted 5 types of crypt., red rubin & melon swords, sagittaria, anubias kwango minima & nana petite. Lighting is from a single strip light with 2 new t8 coralife nutrigrow 25w 36" 6500K range bulbs. Light is positioned over the back half of the tank where the plants are & is on 15 hrs. Fish were then added. I fertilize once a week using Brightwell FlorinMulti. The crypt. harteliana, blassii, &willisi are not doing well. The leaves die & melt away & new leaves are slow coming. After 2 months I would expect full plants with new runners. The swords are holding their own & the sagittaria is slowly pushing out some runners. I had many tanks before all lighted with flourescent Sylvania grow lux bulbs & had C. haerteliana in all of them all started from 6 plants given to me. Why can't I get it to grow now? Do I need to go to a HO t5 fixture & if so does anyone make a single bulb unit so I could buy 2 and spread them apart. As Hoppy pointed out a 2 bulb unit is too bright over a 18' deep tank.