OK, cool thanks :) currently i'm also adding around 5-6ml of TNC complete a day. Not sure how much Mg and K this would be adding... Tank is probably 160-180L.
Just had a Google and TNC complete is:
1.5% N, 0.2%P, 5% K, 0.8% Mg, 0.08% Fe, 0.018% Mn, 0.002% Cu, 0.01% B, 0.01% Zn, 0.001% Mo...