In the first two parts we looked at what plants need and how to classify your aquarium. This final part turns that into practice: which water values to aim for, how to work out how much fertiliser your tank actually uses, and which dosing system suits you best.
Target water values
These ranges suit most planted aquariums with CO2 injection. Low-tech tanks can run at the lower end.
- Nitrate (NO3): 10 to 25 mg/l
- Phosphate (PO4): 0.5 to 2 mg/l
- Potassium (K): 10 to 20 mg/l
- Iron (Fe): 0.05 to 0.1 mg/l
- Magnesium (Mg): 5 to 10 mg/l
- CO2: 20 to 30 mg/l (green drop checker)
- GH: 4 to 10 °dH; KH: 2 to 8 °dH
A ratio of roughly 10 parts nitrate to 1 part phosphate is a good starting point. Monitor CO2 continuously with a CO2 drop checker.
Working out what your tank uses
Every aquarium consumes nutrients at its own rate, depending on light, CO2 and how many plants it holds. The most reliable way to find your dose is simple:
- Do a water change and dose to reach your target values.
- Measure nitrate, phosphate and potassium (or iron) again after 3 to 4 days.
- The difference between the two readings is what your plants used in that period.
- Divide by the number of days to get a daily consumption, then dose that amount.
Repeat the test every few weeks, because consumption rises as plant mass grows and falls after a heavy trim.
Choosing a fertilising system
Basic set: all-in-one
An all-in-one product is the easiest place to start. LGND Avalon provides macro, micro and trace elements together, and LGND Elysium combines nutrients, vitamins and micronutrients in a single, balanced formula. One bottle, one dose, and ideal for low and medium-tech tanks.
Single components
Fast-growing, high-light tanks often consume nutrients in proportions that a fixed blend cannot match. Here, separate bottles let you correct exactly what is missing: LGND Nitrogen, LGND Phosphat and LGND Potassium for the macros, LGND Florebit Ferrum Fe for iron and LGND Heaven for trace elements. This takes a little more testing but gives full control.
Special additions
Some tanks benefit from extras on top of the basic nutrients: LGND Root Wellness tablets for heavy root feeders such as Echinodorus and Cryptocoryne, LGND C5 Eos as an additional carbon source, and LGND Essential or LGND Revival as growth and vitality boosters.
Water
Your water is the foundation for all of this. Tap water often contains enough calcium and magnesium, but may also carry nitrate or phosphate. If you use RO water, remineralise it with LGND Evenness or LGND Balance RO Base so plants have the hardness minerals they need. Weekly water changes of 30 to 50% reset any build-up and keep the system stable.
Summary: set your targets, measure consumption, choose a system that matches the effort you want to put in, and adjust gradually. Healthy plants are the best algae control there is.