too much light?

[RockabillyChick]

can low-light plants like crypts get too much light? i have a 10 gallon with 3w/g (two 18" flourecent bulbs) and my crypts are turning yellow. they started turning yellow when i only had one bulb on the tank, and i thought they weren't getting enough light, so i added another, but they're not greening up. should i add Flourish Excell? i don't want to resort to a CO2 system. just seems like too much work. i heard that flourish excell will provide carbon to the plants instead, as well as other nutrients.

[Damon]

They can get too much light but that is not the case here. CO2 is adding to the problem but not the underlying factor. Have you moved them recently? Are the old leaves turning yellow? Are the veins still green? If I had to guess, I'd say you are lacking potassium. A pic would be wonderful. I would get some flourish and flourish excel. Tropica's mastergrow is wonderful also and a great alternative to flourish. You'll still want the excel in either case.

[RockabillyChick]

i haven't moved them since i first put them in there. i know crypts have a tendancy to "melt" when they're moved, but mine never did. they lost a couple of the outer leaves, but thats normal.

no, its the new inner leaves that are coming out yellow. i don't know what the potassium levels are in the tank though. but the water where i live comes from an aquifer, so its very mineral-rich.