Originally Posted by Wasserpest
Most of the commercially available aquarium plant nutrients do not contain (at least in noticeable amounts) Nitrates or Phosphates. Yet both are required for healthy plant growth.
Adding nutrients per se does not lead to algae, however, if your plants are already dying, or some other nutrient is missing, it might seem like it. Google "Liebigs law of the minimum" for a good visualization.
Plants need ALL nutrients in small amounts. Adding something every 4 weeks seems not a very good approach. Most of us dose DAILY.
So... my recommendation would be to get some KNO3 and KH2PO4 (if available where you live), read up on dosing, and then start in small amounts, and monitor your tank over longer periods. Yes, initially you might get an increase in algae, as your plants are not in their best shape to process the nutrients and grow. Perhaps adding some healthy plant mass along with the nutrients would be a good idea too.
ok dear Wasserpest
1- i started adding the planta Min daily 2ml, it contains iron, manganese, potassium & other macro nutrients.
i will ask about the KNO3 , KH2PO4 at agriculture stores but my be they don't know the dosage because they don't know about fish and water plants.
2- my water test shows that i have high levels Gh 16 Kh 20 and No2 about 1.5 tommorow i will get Ro water Tds 25
and change 50% of the tank to lower the Gh and Kh but why i have high level No2 ?? and how do i solve these things