adding nutrients for plants

hey everyone.. well its been about 2 weeks now.. my tank is crystal clear without any chemicals.. and all my numbers are 0 including my Nitrates.. which is why I have a question.. I can tell that my plants are loosing a bit of colour... I have 4 watts per gallon.. CO2 injection.. but since my nitrates are so low I thin khtey are starving for nutrients.. do you guys reccomend adding anything for this?? My CO2 kit came with this iron additive... What do I need to test for besides nitrates to determine how much stuff to add? THanks guys I got a lot of money in these plants i dont want them dieing hehee and i know i have taken every step except for food.. everyone on here said my tank is too overstalked but obvisouly not i guess..

 

The reoson you may see that you have so little NitrAtes is because the plants can absorb those NitrAtes and use them, just like they use the CO2 injection. Your tank is probably overstocked, bit because it is so heavily planted, the plants are more than likely absorbing all those NitrAtes. I couldnt tell you why they are losing color. They may possibly be getting too much CO2 and light. It is tricky to get them the right amount but if you undershoot or overshoot that amount you will more than likely see a decline in your plants health. -tl