Ok, I am going to get some fertilizer for my plants from here - http://stores.ebay.co.uk/Sunshine-Gardens_Fertilizers_W0QQcolZ4QQdirZQ2d1QQfsubZ3QQftidZ2QQtZkm Would the 20-20-20 water soluable stuff be ok? If not, which one would be best? (For an outdoor grow in pots) Thanks.