Here is an article on building these units. Maybe something will be useful. It allows for overflows of the yeast and also suggests some good ways to get the CO2 into the aquarium.
http://www.qsl.net/w2wdx/aquaria/diyco2.html

When we deal with algae, we look for a growth limiting factor and try to keep that "low" in an aquarium. That is one of the reasons why marine aquarists increasingly use RO water and mix their commercial marine salt mix in it. Many tap waters have more than enough phosphorus or phosphates in them. The marine salt mixes don't have much, if any (some will get into the tank anyway when fish digest food).

When we look to give our plants a comfortable environment to grow in, we look at those same factors. If a plant isn't thriving, we look to "growth inhibiting factors" and try to increase the factor we think might be lacking. These include light intensity (how close to a tank the light can be suspended make a huge difference), how many hours a day the light shines. If your Java fern is off color look first to water quality, then at lighting.

Plants also feed upon nitrogen. Ironically many plants find ammonia easiest to absorb, but if your tank is heavily planted, you fish should be healthy just because of the way the plants act as ammonia sponges. Some plants first utilize nitrites or nitrates, but most can use them only with a great spending of energy on the process. I'm always amazed that aquatic gardening people ADD ammonia to the water because their modest fish population may not produce enough. For those of us without a heavily planted tank, look at the ingredients in any plant fertilizer package because you don't want to add it if there is ammonia in it!

New growth on Java ferns (Microsorium) is a lighter hue of green than are the older leaves (fronds). If it looks lighter like the cooked pea shells (while feeding peas to selected livebearers and killies), then there is a problem.

Some things to consider:

Light and dark (Photosynthesis & respiration)are both important.  Maybe have the lights on 14 hours and darkness for 10.

Periodic partial water changes "preferably from the tank bottom" removes harmful materials, offers nutrients & trace elements and removes harmful stuff, restores pH, and cuts down on harmful bacteria.

High light plants need to be placed towards the middle of the aquarium. One should make a hole on the gravel, place the plants in the hole and gently move the gravel (substrate) gently in around the roots.

Proper planting includes removing plants from the pots they were sold in. carefully, poke holes and place plants gently in them. Java fern and moss are exceptions to that rule and can be placed upon the gravel or lightly attached to a surface (such as driftwood) with a plastic tie or rubber band. (Later the attaching material is cut with a scissors and removed.

A heating cable in the substrate of the aquarium is expensive but will keep the roots warm. One can also temperature control a room - which if you have several plants will be cheaper than heating each tank. A consistent temperature in the 72-78 degrees F (22-25.5 C) may be best. I was surprised that high temperatures were not recommended.

If possible, plant younger plants. As with young adult fish, they are more adaptable.

I know very little about fertilizers and the exact proportions of minerals and elements in the water. But they are important and often best replaced with water changes. To insure iron and trace elements to some potted plants, a little black soil (not around any insect or plant poisons) may be taken from a yard and placed around a plant's roots. The top of the pot is covered with gravel so everything does vault out into the aquarium. Other people will use specific aquarium fertilizers or even gravels in that pot.

Tap waters are pretty essential rather than bottled water with three, but only three key elements (calcium, potassium and magnesium).

Equilibrium, RO Right, RO Vital, or Electro Right are often used to remake RO water. Scott Lockwood's use of marine salts when adding salt to his tanks, adds a lot of sodium, but also quite a number of key trace elements.
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If Java ferns are the only plants in the aquarium, I'd certainly not bother with a CO2 unit, though in a more balanced set-up, Java ferns can benefit from CO2 infusion. I would just look to see why the Java ferns aren't doing better. Incidentally they can be poisoned if medications are left in the tank for a long time. As you know, partial water changes can dilute the meds. Activated carbon (which I almost never bother with anymore)in a filter should absorb/bond the rest of the medications.

In really funky tanks, even Java fern can die. That doesn't sound like your tank though.

In a frustrating case or two, where Java fern or Java moss have become infested with hair algae, I have rinsed the plants, pulled off as much as possible and put the plants in a plastic bag with low mineral water. The bag is put in a corner, out of the light for a few months until the hair algae is history.

Because that doesn't really benefit the ferns, I have taken to moving 2 or three American flag fish into a tank, after pulling most of the hair algae out and gravel vacuuming the tank. Following a 45% water change, the flag fish are acclimated and not fed a whole lot. They have been pretty remarkable in pulling and eating hair algae, while leaving Java ferns and Java moss alone!

A chemist who makes up thousands of gallons of water for desert pupfish, has a recipe for water which is a lot harder than we would want for our guppies. But in general, his sources would work for our livebearers. We just don't happen to keep our fish in a greenhouse of 50 and 100-gallon (and larger) vats and agricultural watering troughs with water two or three times the hardness of our tap water. ;)

He adds a certain amount of synthetic sea salt (Instant Ocean) for the trace elements (the ocean has about 80 elements in the water) even though the vast bulk of it is sodium chloride and then includes measured portions of "anhydrous calcium chloride (Prestone Driveway Heat), sodium bicarbonate (Arm & Hammer), potassium chloride (salt substitute or potassium chloride water softener pellets - 40# bag from Sears - lifetime supply) and an iodide supplement (Kent Marine).
The hard to find item is magnesium chloride.  I use a product called MAG which is flaked magnesium chloride."

Seachem makes a product called Equilibrium, which is used to return safe and necessary minerals to RO water (which by itself will flat out kill fish). Plant people will add just a little bit per gallon and when I look at the flowing growth I can kind of see why:
Guaranteed Analysis (Amounts per 1 g)
Soluble Potassium (K20) 23.0%
Calcium (Ca)8.06%
Magnesium (Mg)2.41%
Soluble Iron (Fe) 0.11%
Soluble Manganese (Mn) 0.06%

Source
http://www.dtpetsupplies.com/catalog/product_info.php?products_id=696

These are among the things necessary for plant growth. If your municipal water source is a river system, reservoir or lake, these are probably in good supply. A certain amount may be taken out by plants or chemical processes within the aquarium. Partial water changes, as often as we can make them, usually replace these substances.

In most cases we do not need to mess around with water chemistry. Just do partial water changes and vacuum the gravel regularly.

You also want to look at your lighting. Duration is as important as intensity. 10-12 hours of light should be minimum. Summer days are longer and some tropical fish are even more likely to spawn if the lights are on for 14 hours a day. If there is not too much light, that will certainly not hurt the plants.

I have to smile when I note the role of vacuuming the gravel. A certain biological culture will still be established in the gravel. That is why,unless one is fortifying the tank with a fertilizer layer in the gravel and maybe special gravel within the gravel) one really doesn't want to plant hardly an of these beautiful Cryptocoryns or Crypts in a new aquarium. The biological system in the gravel will not do much for them.

One book suggested that the hardiest Crypt is the prolific crypt or C. affinis. They suggested that affinis could be planted in a tank as early as six months after the tank was established. Other Crypt could be introduced after a year...

I would suggest that you might add some hornwort and Valisnaria (eel grass) as plant starters to your livebearer aquarium. Both groups of plants (there are several species of Val) tolerate a wide range of light and are hardwater plants, good with livebearers. They both, given light, can be fast growers and they will absorb waste products from the water in quantity. In fact, you may have to take scissors and trim back the Val and maybe discard the ratty ends of the hornwort. In aquariums, Valisnaria reproduces vegetatively, sending out runners which will produce a new plant every couple of inches. (The process is similar to the spreading of strawberry plants in a conventional garden.) Probably when there are too many val, you can bag up a dozen or three and take them to your LFS.

Conventional wisdom is that new aquariums should be planted heavily. This might be several dozen plants to a 10-gallon tank. When we only plant five or six plants in a ten, we are inviting an algae bloom.

http://www.csd.net/~cgadd/aqua/art_plant_newtank.htm

is just one of many articles which will come up when one Google searches for Setting Up a New Planted Tank or aquarium. One of those articles suggested that if a person was to effectively plant a 75-gallon aquarium, they could plan on spending $500! The light fixture for that tank could run $250.
http://en.allexperts.com/q/Freshwater-Aquarium-3216/Starting-planted-tank.htm

I too go into sticker shock when reading stuff like that. I put a bunch of plants under 2 or 4 tube fluorescent fixtures. Someday, the compact fluorescents will be explored. I take plants from smaller established tanks and colonize. Cuttings and young plants can be rooted. Little is thrown away. One can start with a bunch of hornwort or water sprite, maybe with a under layer of Najas or Java moss and build from there. One could also go with a few bundles of the fast growing "bunch plants" or "oxygenators" of the pond crowd. (Plant them soon after purchase so they stay healthy.) As the tank matures, some of the fast growers can be cut back and slower growing plants can be added - perhaps to the sides or back of the tank, where there would be less light. Since my interests lay mostly with breeding and raising fish as opposed to aquatic gardening, that works for me; a real water gardener probably would be insulted by that unambitious approach.