Well for one thing it varies according to what you're growing.

Can't really give much advice on the NPK ratio or nutrient concentrations without some idea what you're growing.

Tomatoes, specifically Siletz, a determinate, parthenocarpic variety. The fertilizer is something like a 5-30-10 plus I add a multivitamin a week in a 4-gallon bucket. (Don't laugh - it works great because it has lots of the micronutrients needed).

Mike

Perhaps this link will help: Jim Taylor's Three Part Hydroponic Nutrient Formula for Vegetables

Hi greystoke,
The author of your link kept Phosphorus constant; ie: never elevates P for a "bloom" nutrient solution. Yet many people are convinced "bloom" formulations (high P ratio) are the best strategy.
? Do you have any experience altering the P content ?

I checked the solution today and it was 780 ppm. The plant has several pre-blooms on it.

Mike

Sounds good. Tomatoes typically like a heavy feeding schedule so I'd bet you could up that ppm by at least 50%, probably 100% or more.

If it was mine I'd probably up to 1000ppm, assuming the plant has a few true leaves on it already. In my experience tomatoes don't require a radically different feeding regimen during fruiting since they are still growing vegetatively during that process as well. I'll add in some PK boosters like Big Bud and carbohydrates, just to make sure the plant has extra resources and energy readily available, but I like to have a more balanced main nutrient doing most of the work.