Pruning, trimming, and thinning of plants.
Constant work is required to shape the canopy of aquatic plants, otherwise they will turn into an untidy, overgrown garden. This is not only a matter of maintaining the correct composition in the aquarium, but also a matter of the health and beauty of the plants. The growth and size of plants must be kept within desired limits at all times. The period during which you can keep the aquarium in proper condition also depends on the number of fish in it, their species composition, and the feeding method.
When plants are healthy and thriving, they will eventually fill the entire aquarium, and it will look like a disheveled lawn. They should be periodically pruned and weeded, and those appearing in unintended places should be removed in a timely manner. It is necessary to ensure that they do not shade each other and smaller plants growing underneath them. Old leaves must be removed all the time, tops cut off, and after removing the old stem, plant top cuttings in its place.
Pruning plants is a great stimulus for their growth, as it allows them to get rid of old leaves and get the energy and incentive to grow new ones. Scissors should be 
as long and sharp as possible. The cutting part is slightly curved in an arc, so you can even trim small foreground plants with them. The shape of the scissors should allow you to prune plants without destroying them. The thinner and longer the scissors, the better you will trim plants in hard-to-reach places, and long handles will allow you to reach the most complex and difficult areas. Pruning is usually done in close proximity just above the node (a small stump of 2-3 millimeters). You should not squeeze the plant with your thumb and forefinger, crushing and tearing the stem, as a result of which new shoots may start in an unplanned place.
When cleaning from algae and trimming plants, you can use a paint roller tray – place it on the water surface, hooking its legs onto the wall of the aquarium. You can also find a very suitable paper tray. A transparent one is more convenient because it does not shade the aquarium below it. The bottom line is that with a tray, to remove trimmed plants and algae, you no longer need to move your hand outside the aquarium: water does not flow down your elbows or the aquarium. It is also convenient to put tools on it.
Why limit plant growth. The fact that algae is not visible in an ideal planted aquarium does not mean that it is not growing. Algae is always present in any aquarium. Completely stopping the growth of algae is simply impossible, because in any healthy water body with plants there is plenty of everything needed for algae growth. They need the same macro- and microelements, CO2, light, organic nutrition, humates as plants; green algae have the same type of chlorophyll, and the zones of optimal conditions for plant growth and “green” algae overlap.
You prune and remove a portion of the plant biomass; the remaining ones grow rapidly again, constantly consuming nutrients, and prevent algae from dominating. However, it takes time to restore the sharply reduced plant biomass, and it is during this period that a rapid accumulation of excess ammonium (the main stimulant for the start of algae growth) occurs and an imbalance can arise. Accumulated phosphates, although not a direct cause of algae appearance, greatly accelerate their growth. That is, during an imbalance, you need to have as few phosphates in the water as possible.
Frequent trimming causes sharp periodic decreases in plant biomass growth, and this gives much more chances for algae to appear. Continuing to add micro, NO3, and PO4 in the same doses will increase their concentration in the water, which will greatly accelerate algae growth. Large fluctuations in biomass and the difficulty of selecting the correct dosage of liquid fertilizers before and after trimming often lead to imbalance. It is light that sets the pace of photosynthesis – not the presence of N-P-K and not CO2!
By reducing the duration of the intense photosynthesis period, we will reduce the plants’ need for nutrients, and ensuring their sufficient quantity without the danger of algae will become much easier, especially with a rich substrate with high CEC. As a result, stability will increase significantly. It is better to limit the time of intense lighting or illuminate only with high-intensity light for 6-8 hours if the aquarium is lit only by MH-HQI lamps. Do not do a large weeding all at once, it is better to divide it over several days. Start feeding plants after new signs of vegetative growth appear. A sharp decrease in biomass can lead to an imbalance in your aquarium.
Stem plants – for example, Hygrophila – generally tend toward the water surface. Usually, they grow to the water surface and then stretch even higher or creep along the surface. In this case, the lower part of the stem is often relatively or completely devoid of leaves and looks unattractive. Such plants need to be pruned so that they produce side shoots. Never pinch off the top of the stem under water, as this slows down plant growth. Some plants, for example, Vallisneria, reproduce by runners and can quickly fill the entire aquarium with their lush greenery. Such thickets need to be thinned out regularly.
Stem plants grow relatively quickly. If this is not prevented, soon the overgrown branches reach the water surface, and the plants begin to hang parallel to the horizontal line. If the growing tips of these shoots are cut, they will also begin to branch. As a rule, new shoots develop within a week or two after pruning. This time there will be several shoots emerging from the leaf axils below the cut. As a result, instead of one long thin stem, an attractive bushy plant will be obtained. When pruning only the tops, two or three new leaves will grow, but the plants will have a very top-heavy structure and will start to break after a few prunings. If this starts to happen, start pruning the plants less often but lower down.
Cut parts of plants can be used as cuttings to grow new plants. It is necessary to trim such plants as early as possible, because conditions in the 
lower stem zone deteriorate as soon as the plant reaches this point. In the bottom area, where light penetrates poorly, stem plants eventually lose their leaves, release roots, and become unsightly. To hide this part, Cryptocoryne and other aquarium plants are planted in the midground. Driftwood is used for the same purposes.
Stem plants need frequent trimming. Stem plants should be pruned to the desired size, keeping an eye on the balance of the entire composition. During the first trimming, let them grow to within 10 cm of the water surface, and then prune them to half their height. With each subsequent trimming, cut the stem slightly higher than the previous cut point. One or two shoots sometimes begin to grow faster than all the others. If this happens, such shoots should be cut off immediately. Two or three new sprouts will grow at the cut site, so the plants may become too lush at the top after excessive pruning and the stems will easily break.
If this starts to happen, trim the plants less frequently and higher up the stem. When trimming stem plants, it is also important to give a certain shape to the surface of the bush. Paying attention to how they grow, you should trim the bush so that stem plants form a beautiful “cap” during growth within two to three weeks. The rest of the plants are trimmed simultaneously with the stem plants so that they develop proportionally.
Plant care after trimming is also important. Although stem plants are relatively insensitive to pruning, the lower parts of the stems near the root zone begin to age, and new roots are formed rather heavily after several prunings. Over time, even stem plants reduce their ability to produce new shoots after many prunings. If a stem plant is too old and the base of the plant begins to rise from the substrate, then the entire plant is completely removed, the old lower part is cut off, and the young upper part of the stem is replanted.
You can enjoy stem plants for a long time thanks to trimming and rejuvenating plants in this way. After pruning plants, it is necessary to reduce the amount of fertilizer applied. Such adjustments to the amount of applied fertilizers should be made taking into account the volume of plants and their condition.
