Neutro Boost is a powerful, clear plant fertiliser containing nitrogen and potassium (macronutrients), which is designed to be used alongside Neutro CO2 and Neutro T or Neutro+. If you have a CO2 infused aquarium, uptake of nitrogen and potassium happens surprisingly quickly - plants can grow fast and need a lot more food so they can stay healthy and sustain the required pace of growth. Maintaining these macronutrient requires regular dosing. In addition to that, it's good practice to ensure water circulation is excellent (so fertilisers are moved around) and replace at least 30% of your aquarium water per week (as a minimum).
So what do plants need nitrogen and potassium for? Nitrogen is a major component for chlorophyll (plants use this combined with light to produce sugars) and a major component of amino acids (protein building blocks). Without these proteins, plants simply die. Potassium on the other hand regulates the opening and closing of stomata, (controlling CO2 uptake) and also functions in other physiological processes such as photosynthesis and protein synthesis. Potassium is considered second only to nitrogen when it comes to the nutrients required by plants, so you can see why, if your plants are deficient in these macronutrients, it's not looking good for them.
Visual Clues: An obvious sign of a nitrogen deficiency is poor plant growth and / or yellowing leaves. Potassium shows up as holes in leaves and / or dying / curled leaves. If you see unhealthy plants with leaves such as this, the sooner you dose Neutro Boost, the better. Acting fast is a solution but prevention is always better than cure. Once plants display a deficiency, the problem leaves rarely recover, but it's the new growth that you need to focus on. Remove unhealthy leaves and dose as below and don't forget that nutrients DO NOT cause algae.
Dosage: Add 10ml per 100L two or three times a week - this will increase your nitrogen levels by 4ppm (per dose) and your potassium by 2.5 ppm (per dose). Target level for nitrogen is 20-80ppm and potassium 5-50ppm. For experienced hobbyists you will be able to approximate how much to be dosing without testing. Look for early signs on new plant growth and as your plants grow, they will need more food.