What fertiliser should i use for soil NPK

Hi,

i currently use levington tomatoe liquid fertiliser for my plants in 15 litre containers with soil... NPK 4 - 4.5 - 8. I use this whilst plants are flowering during veg i normally just use miricle grow lol
My last grow harvested 0.5 grams per watt all the plants looked healthy and the smoke was great but im wondering if there is anyway to increase my yield without changing to hydroponics as all the other conditions are spot on i.e temprature humidity ect...
Does anybody have any ideas on what fertiliser i should buy?? I read in a grow book that a fertiliser with an NPK around 15 - 30 - 30 is good for flowering but the levington tomatoe fertiliser is the closest i could find....
Any advice would be great

Use a more balanced fertilizer, i go with 10-15-10. The number one yield increase for soil would be the over all vigor of the plant. You could top it (LST), keep the soil aerated to bring oxygen to the roots, pay close attention to growth and care for the plant intensely, and veg for a longer period. All of these will amp the over all size and strength of the plant.