I would like some dosing and fert/trace suggestions.

I have a 1.75w/gallon 120G with a eco-complete substrate. Run an Ehiem filter in one corner with a power head in the opposite, about midwater. Run the lights about 9hrs day. It has been up about 8 months.
It is heavily populated with very happy mollies who are prolificly breeding.
The ph about 6.5, Nitrites 0, nitrates 20 mg/l, according to strips, GH 180 KH ~180.
I started with swords that were melting rapidly and thin anacharis and was doing water changes (which I have all but eliminated) about %25 weekly.

Anyway, started dosing potassium nitrate at 5/8tsp and monopotassium phosphate at 1/8tsp and Seachem equilibrium at 5/4 tsp all per week.

Then I got an Instant Ocean Phosphate and Nitrate kit. I noticed Phosphates over 5 mg/l and NO3 at 80mg/l!. Since then (4 months) I quit adding the phosphate and nitrates, used Nitrazorb to get it down to about 1mg/l, and the nitrates are down to about 20. I only feed about 1/day or 1 every 2 days

The duckweed has come back in full force, wysteria is growing ok, but curly and stunted with dark (algaeish) edges. Anubias has spot algae but has had new growth, the crypt. lutea seems to be real dark , almost brown/green. Rosanervig is growing, but again curled under and oddly formed leaves with algae edges. The anacharis is booming with only the older growth thinning. Swords are still thin, slow growning.

I know I am missing trace, because of only top offs and filter cleanings. So I need a suggestion on trace elements. Also, should i be adding some iron or something else here? I know I am missing something, but my rookyness can't filter through it.

All help is greatly appreciated.