Sorry roadmaster i am not able to find the original info anymore (do not remember where). If i find it i will post it.
I am a user of Metracide and Excel as well. I finish my last Metracide bottle and i think i will just use just Excel after that. 50 CAN$ for a 2 liter and i calculate that i am able to do 1 year at normal dose. My tank is 240 liters (more 200 liters of water if i calculate substrate, rocks, and roots). It is within my budget and acceptable.
Michel.