[lauraleellbp]

Actually, the Hagen 18,000k DOES support FW plant growth. If you look up the bulb specs, it has a nice red peak. I happen to quite like this bulb, especially in combo with a different spectrum bulb for great color rendition in a tank.

A picture of your tank would definitely help, but several of the plants species you posted are not ones that will usually do well in a non-CO2 setup, such as Glosso, the Eleocharis sp, and that species of Lilaeopsis. I personally think that you already have enough light on this tank for a successful low light setup- if you work with a better selection of plant species.

Water movement can help distribute nutrients around a tank and filtration- especially mechanical filtration- can help avoid debris buildup. Pockets of debris will decay and fuel algae growth.

It's definitely possible to set up successful planted tanks without any circulation or filtration, but it's generally easier to find the balance you need for healthy growth with the help of equipment.

Based on the info so far, my own opinion is that your struggle is most related to plant selection than anything else at this point.

 

[lauraleellbp]

The way I see your options are:

1) If you want to stick with your current plant selections, you'll most likely need to increase your lighting and start using CO2 + a balanced fert regimen to see them do well

OR

2) You can stick with your current lighting, no CO2, and switch most of your plants out with hardier plants that are better adapted to lower light and non-CO2 conditions

Over the years I've run several 10gal tanks under your current fixture with the same T8 PowerGlo bulb and no CO2. Crypts, mosses, Java ferns, Sagittaria, Hygrophila, Hydrocoytle, Rotala rotundifolia, and sword species have all done great for me (usually didnt take more than a few months for the swords to need tank upgrades LOL).

 

[lauraleellbp]

Desperately trying to stay low-tech here, but really like the eleocharis species and the echinodorus tenellus. Right now I think the plan is to try to keep these plants alive and if I can't then make other plans later.

The chain sword will probably do fine. The hairgrass probably needs more light and CO2. Definitely try it an see, though, YMMV.

I switched the 1x15w power-glo to a temporary solution with 2x18w of sylvania warm-white. So it is more light, but not the best light. Will this cause new problems?

In what kind of fixture? I'd have to look up those bulbs to be sure, but from the photo, I doubt those bulbs are a good spectrum for plant growth. Most bulbs in the 5000-10,000 kelvin range will support freshwater plant growth. Those yellow bulbs are likely much lower kelvin, though. You're likely better off with the 1x15 T8 fixture with the aged PowerGlo than that one.

Or you could possibly could get different bulbs...if the "new" fixture takes U-shaped CFL bulbs, you'll likely need CO2 to run along with it. If they're spiral CFLS, however, you're probably good without CO2.

Again... a LOT depends on the specific fixtures and bulbs in question!

I'm thinking about trying to order LED stuff from ebay and try to fix a diy led fixture.

Don't want to discourage you, but also don't want to see you waste money- you need to research LEDs very carefully before going the DIY route. Only very specific ones put out the type of light that will support freshwater plant growth.