Bio-Green is a plant fertilizer containing iron and other trace elements to feed and fertizlize your aquarium plants.
Ok, it's actually an aquatic fertilizer - good!
That description suggests it doesn't supply macro nutrients. The macro nutrients that plants need are nitrogen (N), phosphorus (P), and potassium (K). And they need lots more of those than iron or other trace nutrients.
Some of that is provided by fish waste, but usually not enough.
Other than the possibly terrestrial plant that Hoppy spotted, the yellowing could be a symptom of several possible nutrient deficiencies, nitrogen and potassium among them. I use this
as my diagnostic checklist.
Potassium is probably the most deficient in your tank.
Directions: Each week add 5ml per 20 litres of aquarium water, or for the best results, test the aquarium water with an iron (Fe) test kit and bring the iron level to 0.5mgl, 250ml will treat 1,000 litres.
0.5mgl is a bit high, most people aim for 0.1-0.2mgl; but I don't think it's high enough to cause problems. It's probably safe to assume the Bio-Green is providing plenty of other micro (aka trace) nutrients too.
You just need to supplement with the macros (NPK) too.
Lastly what other advice would you give me, stick with what i am doing or switch to low light or low co2 plants.
Plants matched to your tank are always easier. Low-light, fast-growing plants are your best bet. But that doesn't mean you have to throw out what you've got; solve the nutrient issues and you may find success with them too.
There's really no such thing as a "low CO2" plant. Light is the main variable. As light goes up, plants need more CO2 and other nutrients. If they don't get what they need, the plants will suffer and the algae will thrive!
In a low-light tank, CO2 from the air and fish can be enough to avoid problems; although the plants will still grow faster if you provide extra CO2.