You have a foundation and the right light. Now you need to feed your plants. Fertiliser is where most planted tanks go wrong, either by feeding too little and getting weak growth, or by feeding too much and getting algae. This is Part 3 of the Planted Tank Series, and we keep it simple.
What Plants Actually Eat
- Macronutrients: nitrogen (N), phosphorus (P) and potassium (K), plus calcium and magnesium, which come from your water's GH.
- Micronutrients: iron and trace elements such as manganese, zinc and boron.
- Carbon: covered in Part 4.
Fish waste supplies some nitrogen and phosphorus, but in a densely planted tank with strong filtration it rarely covers everything.
Water Column vs Root Feeding
Stem plants, floating plants and epiphytes such as anubias, java fern and moss take most of their food from the water. Rooted plants such as swords and crypts feed primarily through their roots. Most tanks benefit from both a liquid fertiliser and root tabs.
Which Fertiliser for Which Tank?
|
Tank type |
Approach |
Option from Aquarium Products India |
|---|---|---|
|
Low-tech, no CO2, few plants |
All-in-one liquid, low frequency |
Sunken Garden Green (all-in-one, works with or without CO2, anti-algae formula) |
|
Dutch-style, bushy stems |
All-in-one for dense growth |
Sunken Garden Vibrance (Dutch-style, works with or without CO2) |
|
High-tech with CO2 and strong light |
Full macro and micro dosing |
The 2hr Aquarist APT Estimative Index, APT Complete |
|
Heavy root feeders |
Root tabs |
Root Boost+ (Plants Right Series) |
Dosing Rules That Prevent Algae
- Follow the label and start at the lower end of the dose.
- Increase slowly, only if growth is healthy and no algae appears.
- Dose on a fixed schedule, for example after your weekly water change.
- Match fertiliser to light and CO2. More light and CO2 can utilise more nutrients. Less light needs less.
- Do regular water changes to reset nutrient levels and prevent build-up.
- Keeping shrimp? Check the fertiliser label before you dose.
Reading Your Plants: Deficiency Guide
|
Symptom |
Likely cause |
What to do |
|---|---|---|
|
Older leaves pale or yellow, slow growth |
Low nitrogen |
Raise the macro dose slightly |
|
Pinholes and yellow edges on older leaves |
Low potassium |
Raise the macro dose slightly |
|
New leaves yellow with green veins |
Low iron |
Add or increase micro or iron dosing |
|
Twisted new growth in very soft water |
Low calcium or magnesium |
Test GH, see Part 3 of the Water Parameter Series |
|
Green spot algae on glass, plants growing slowly |
Low phosphate or imbalance |
Review dosing and reduce light slightly |
👉 Shop Sunken Garden Fertilisers | Shop The 2hr Aquarist | Shop Plant Fertilisers & Additives | Next: Part 4, CO2 for Planted Tanks
