Advice on liquid fert & Iron tappings

[asdman]

any 1 can reccommend any good brands of liquid fert & Iron tappings??
Best is cost -effective ( meaning using a small dosage to treat larger volume of water)

Tank Specs:
4*2*2
Eheim 2028
co2 tank..2bps
around 170 watts for lighting
Lots of plants


thanks

[|squee|]

What do you mean by iron tappings?