Hi,
Just a minor clarification to what Paulo mentioned TPN contains only micronutrients, while TPN+ contains micronutrients + NPK. I see no point whatsoever in buying both, because TPN+ is an all in one product.
Regarding the original question, it is not possible to say with any certainty what the dosing should be for any commercial nutrient product. The reason is that all name brand products, including TPN/TPN+, are very weak and the bottle dosing recommendations are only valid for low light, non-CO2 tanks. When you step up the high light, CO2 injected tanks then you need to start multiplying the bottle recommendation by factors of 2 or 3. What may work for someone living in an agricultural zone will not work for someone using RO water. Commercial nutrient products are so weak that success in using them is highly influenced by the level of nutrients in the water supply. That's because tap water from different areas of the country will have different levels of nutrients in the water supply. The hobbyist in an agricultural zone may not realize that he/she is lucky from that perspective and that it may require much less TPN/TPN+ to achieve good growth performance. This hobbyist will then recommend his/her dosing to someone whose water supply is low in nutrients and that hobbyist will not have as much success.
As Paulo mentions, this is why dosing with dry powders is not only vastly cheaper, but gives you ultimate control and provides for a better success rate because you can make a nutrient mix of any strength desired, independently of the nutrient levels in the water supply.
Cheers,