[david meyers]

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.

 

[Hoppy]

At 18 inches, a typical one bulb T8 light will only give you around 10 micromols of PAR, which isn't enough for aquatic plants. Two side by side bulbs would give about twice as much light, but over only half of the length of the tank. And 20 micromols of PAR is barely enough light, if it is enough.