Vallisneria americana can't be sustained in my 100 gallon tank

[Kazumi]

Hey sorry if this is in the wrong section of the plant forum but i just guessed were to post it.

I have been trying to keep Vallisneria americana for a long time but they have only lasted a few weeks before turning brown and dies i wasn't planing to keep these but when i picked up my fish from my uncle he threw a few in since he had to much of them. They are growing fine in my 30 gallon tank but in the 100 they keep dieing.

The 100 gallon has a powerglo and a aquaglo fluorescent lights T8 i think. (says t8 on the package i got them in)
I only use the aquaclo for lightning the powerglo is always turned off looks alot cleaner and nicer with only the aquaglo on.

The 30 gallon has just normal fluorescent lights you buy for next to nothing no aquarium lights at all just normal household lights.

I don't use any fertilizer apart from the fish no need for more atleast in the old days so why need it now.

[Goes to 11!]

You left out some relevant info about both tanks...

Substrate?

Number of, Wattage and color temperature [spectrum] of the bulbs? The more details the better here. [Pics may help]

Stock in the tank?

What are the dimensions of the 100?
:22:

[Aeonflame]

That's strange. Ive been able to grow all species of vals in far less than ideal conditions. The questions stated by Goes to 11 will help

[talldutchie]

Vallis does need some nutrients and it doesn't do that well in really soft water. It's also quite sensitive to various chemicals including too much liquid co2.

[Kazumi]

i don't use any unnatural chemicals like fertilizer or co2. I use fine sand in the 100 gallon and gravel in the 30 gallon. the stock is pretty low now since i just started up after being down for a few month, 3 angels was 4 but had to give one another home to keep him alive 5 corys and 1 ancistrus, 30 gallon has 8 tetras and 1 ancistrus.

the tank are about 5 feet x 20 inch x 20 inch it's abit smaller then this but it's also not a 100 gallon it's a 99.93 gallon to be exact

the powerglo is daylight 40watt 18000k temp
the aquaglo is color enhancment 40watt 18000k temp

[mizzoutank]

18000K???

that is at the top of the reef spectrum for lights. I'm surprised you don't have an algae farm with those.

6500/6700k is the ideal temp for plants as that matches 'daylight' spectrum.

but the combo of no ferts/nutrients and that temp of a light, you won't have too much success with plants.

get a 6500k bulb set up-add root tabs and you'll have a better chance of growing things.

[Goes to 11!]

Just FYI - Both CO2 & the compounds in Ferts are naturally occurring. :11:


the powerglo is daylight 40watt 18000k temp
the aquaglo is color enhancment 40watt 18000k temp
These are T5 or T8 bulbs? Length?

80W of the wrong spectrum over that tank sums up your problem pretty succinctly.

The 18000K is not suitable for plants. In fact, If you had more powerful lighting you would have an algae farm for sure. 18000 is more appropriate for reef lighting and an optimal spectrum for plants would be in the 6500/6700 range.

EI: I have 108w of 6500K T5 lighting over a 55g that is the same height [4' long though].

:22:
EDIT: Ninja'd by Mizz :-P

[Kazumi]

i did a massive error in the lights one is correct but it was a sunglo not a powerglo but im only using the aquaglo never have the sunglo on since it looks to yellow the aqua gives a much clearer look the water looks clearer and the sunglo are only 4200k the lenght of the lights are 122 cm 48" (48" might be american messurement not sure otherwise use a converter not american so not sure how you write inches without writing the word inches)
the lights are t8 40 watt each
the 30 gallon can sustain the valsineria and it has only a normal kitchen light not any special aquarium lights like the 100 has.
I have no problems keeping any other plants like swords,anubis,cryptocorine or java fern

Here are some pictures on the lights in action

The aquaglo only with my wonderfull angel male that is quite huge about 6 inches had a larger angel that was of unknown gender i called it a hybrid acted like both sex and always keept with the large angel male
http://s18.postimg.org/oxjjy3dg5/2013_05_23_16_07_01.jpg (http://postimg.org/image/oxjjy3dg5/)

Both lights turned on
http://s16.postimg.org/e41fot0gx/2013_05_23_16_07_19.jpg (http://postimg.org/image/e41fot0gx/)

Only the sunglo turned on with all 3 angels the 2 nature angels are a pair trying to find a female for the yellow male but i need to get a large or a positive female since my angels has become quite aggressive when my uncle held them for a few month
http://s23.postimg.org/638kf358n/2013_05_23_16_07_37.jpg (http://postimg.org/image/638kf358n/)

The first picture shows how it looks at all times