Are U using fluorescent lights, a substrate that promotes plant growth such as latarite, feeding plants with Iron and other supplements on a weekly basis?
What type plants do you have? Some grow a lot quicker then others...and unfortunately a lot of places sell plants that are not meant for aquariums, they'll live a while but never grow well and slowly die off and just pollute your tank.
Also, are you overfeeding fish, thus high Nitrate content due to dirty tank. Also sounds like you need to vacuum your gravel and clean the glass. Water change once a week, 25%.
Check out plantgeek.net, they have a decent list of plants with pictures and you'll be able to hopefully find yours and see if they are in fact aquarium plants. Had the bad luck myself at first to purchase plants based only on their looks rather then really researching them and ended up with swamp plants that slowly die off and just make a mess of your water parameters and dirty the bottom as they decay.
Algea is virtually impossible to totally get out of your tank and some are actually beneficial, as long as kept under control, brown algea is fine, just looks bad when glass isn't cleaned often.
If you ever get hair algea or black algea......start to cry!
Hope this helps.
priscilla
