Necessary conditions for plant growth.
Continued…
• Use filters with a slow water current, with strong intermittent movement across the aquarium surface. Use a large filter and initially use activated carbon in it. Nitrifying bacteria need time to develop a culture, therefore, rely on activated carbon in the filter. A bacterial culture on a solid surface is the best choice. If the filter is silted up and does not perform its main function—processing ammonium—this stimulates algae growth. The use of special (peat) filter media is justified; they will help maintain pH in a mode unfavorable for fouling or “pH buffers”, as well as phosphate and nitrate “cut-offs”, preferably from well-known Western companies.
• Too much / too little light. Plants do not need just any light for photosynthesis that is visible or pleasant to the human eye. It is very important for them what intensity and what exact emission spectrum the lamps illuminating them have. There must be a sufficient number of lamps with a spectrum suitable for plants. It is advisable to use lamps with a spectrum preferred by higher plants.
What do the growth rate and plant biomass depend on? The plant growth rate, i.e., the intensity of photosynthesis, is determined primarily by lighting intensity. Not the concentration of CO2 or macronutrients, but light! Less light means plants need less CO2, macro-, and microelements. When there is enough light and a corresponding amount of CO2, plants can consume macro- and microelements and grow normally, suppressing algae. The replacement of certain types of fluorescent lamps should be carried out at least twice a year. It has been noticed that even the best lamps operated beyond their designated lifespan provoked algae growth.
The photoperiod should be no more than 10-12 hours with mandatory spectral compliance. With a long aquarium day with low-intensity lighting, algae gain a significant advantage over higher plants because they can grow and feed during the period when higher plants lack photosynthetic activity.
Aquarium lighting must match its height and volume. The sign of trouble is simple: if brown coating grows even in well-lit areas, there is not enough light. There is not enough light that higher plants can consume. There might be other light, but it is of no use to them. It burns to the benefit of diatoms, whose photosynthesis occurs in a different part of the spectrum and at a different intensity.
If you observe a different picture: the leaves of higher plants turn to the light not with their flat side, but with their edge, or fold, closing the apical growth point—it means there is too much light. In this case, green algae usually grow on glass, stones, and leaves of higher plants. After all, while higher plants are “working”, they are able to suppress algae growth by their own means. But while higher plants are resting, green algae take advantage of impunity and photosynthesize.
The light source must be powerful enough to provide a sufficient level of illumination even for the lowest, smallest plants located at the bottom of the aquarium. However, this also means that the lighting level must match the nutrient level in the aquarium. Too high an illumination level will quickly lead to nutrient depletion, especially trace elements. This will slow down the growth of aquarium plants and accelerate the development of primitive algae. Lack of illumination will lead to a halt in plant growth and, consequently, a lack of oxygen in the water.
• Do not buy plants infested with primitive algae. Fully inspect plants before planting them in the aquarium. Before placing purchased plants in the aquarium, they must be treated to prevent the introduction of algae, plant pests, and fish disease pathogens. To avoid introducing algae spores with new plants, it is necessary to carry out their prophylactic treatment.
This can be done using a chlorine-containing liquid that is part of household cleaning products. To do this, dilute a five percent bleach solution in water (1:20) and submerge the plants in it. After a couple of minutes, take the plants out of the solution, rinse under running tap water, and only then plant them in the substrate. However, it should be remembered that this procedure is contraindicated for stem plants with soft leaves. Also, potassium permanganate and hydrogen peroxide have a good disinfecting effect, from which weak solutions are also prepared.
Aquarium plant enthusiasts have probably noticed: when a plant leaf touches the wall of the aquarium overgrown with algae, after some time the algae disappear under 
the leaf. There is a constant struggle for survival between algae and higher plants in the aquarium. Moreover, fast-growing plants often win. Therefore, a known method of combating algae is by placing a large mass of floating plants in the aquarium, for example, Ceratophyllum, or planting fast-growing stem plants.
Use many stem plants initially; they will absorb excess nutrients, carbon dioxide, and regulate the amount of light through their growth. Among the fast-growing ones: Vallisneria, Ceratophyllum, Limnophila, Hygrophila, Cabomba, Hygrophila corymbosa, Rotala, Ludwigia. The number of stem plants needs to be selected; it should be proportional.
Never place plants in mineral wool with a pot into the aquarium—it contains a large amount of nutrients. Aquarium plants purchased in pots are usually grown in greenhouses (semi-submerged). There, the plants remain above the water surface, and the roots are placed in a special substrate rich in nutrients (nitrates and phosphates). This can cause an algae bloom.
Give plants time to adapt after changing maintenance routines. Doing everything “right” in general, following the methodology, but without waiting for algae to die off and stabilization, people make more and more changes to the plant maintenance regime. All changes should be made gradually; the adaptation period should be at least a week or two, regardless of whether you are improving conditions and making them more “spartan”, intentionally limiting plant growth by reducing light and/or PO4 dosage.
• Mechanical cleaning of algae. Along with other measures, the most important part of the methodology for getting rid of any algae is to remove as much of them from the aquarium as possible and immediately filter out all mechanical suspension from the water. Every time the aquarium is disturbed, especially the substrate, and when getting rid of algae, the filter should be washed. Any water pump with a foam sponge can be used. This eliminates the rapid release of ammonium / nitrites / organics into the water and the stimulation of algae. Especially during the aquarium setup stage, it is necessary to check for primitive algae in the tank daily. The appearance of blue-green algae on the substrate or plant roots, as well as filamentous algae on the edges of plant leaves, etc., must be removed immediately.
• For the especially lazy, branded chemical algaecides will help as a temporary measure. The use of algaecides is justified only if the previously listed methods of combating unwanted algae do not help. In any case, the use of such preparations brings only temporary improvement, and sometimes is completely useless and is a “double-edged sword”.
Do not forget that pills cure one thing and cripple another. Almost all types of plants suffer in one way or another from the use of algaecides. And if during the action of the reagent the situation with the above-described factors in the aquarium does not change in the direction necessary for the plants, the algae invasion will inevitably repeat soon. Still, first determine what kind of algae are growing in your aquarium: green, red, diatom, golden, blue-green? Without this, you cannot pick the right pills. And when you determine it, you may cope without pills once and for all.
• Introduce algae-eating fish and shrimp into the aquarium at the start to prevent an algae bloom. It is useful to have in the aquarium: Crossocheilus siamensis, Crossocheilus species, Pterygoplichthys, Ancistrus, Otocinclus, Gyrinocheilus, livebearing fish, Labeo, kissing gourami.
Chemical methods for determining the health of aquarium plants.
How to grow plants, not algae. 
