Maintaining good plant health, and stable parameters are important as it allows plants to grow consistently healthy. Each time growth parameters are changed drastically, plants have to re-program their enzymes to optimize for new conditions. This can lead to premature shedding of old growth or melting of portions of the plant. In such cases, replanting the healthy tops and discarding the deteriorating bottoms is important.
Most planted tanks produce a lot of organic debris that can trigger algae. Having shrimps, snails and microfauna that quickly break down and digest these smaller pieces of organic material is tremendously useful. Regular vacuuming of the top surface of the substrate also important; using a turkey blaster to stir up only the top most layer of the substrate while hovering a siphon above is an easy way to accomplish this.
There are 4 main factors that determine algae absence or presence in a tank.
This is a guide to the appropriate light intensity as measured on the surface of the substrate
30umols of PAR (photosynthetic active radiation): Low light plants such as ferns, mosses, Cryptocoryne, Anubias, Bucephalandra species grow well. If you are growing purely shade plants, it is smart to stay in this range.
50umols of PAR will enable you to grow any commercially available aquatic plant (when coupled with optimal CO2 levels). However, this gives little allowance for shading issues in crowded tanks. Most nature style and Iwagumi style tanks that do not require high density do well at this range.
50 to 150umols of PAR; Colored stems will display better coloration and carpets spread very fast as light levels increase, at the risk of more algae issues. Tank cleanliness and plant health must be maintained at optimal conditions to prevent run-away algae. Allows for increased planting density for light demanding plants. Most experienced aquarists can do well in this range with regular upkeep.
200umols of PAR & above; Marginal gains to plant growth form and coloration starts to be outweighed by large potential instability of algae outbreaks. Might be useful inducing stronger coloration in shorter stems close to substrate; and for farming purposes. Should only be used by aquarists used to maintaining already algae-free tanks.
Proserpinaca palustris is one of the few plants that see improvement in coloration/form with very high light levels. Most colored/red plants can be grown well without such excessive light.
Minimum of 5-6 hours for new tanks that want to minimize triggering algae.
7-10 hours is common for average, stable tanks.
10+ hours; marginal gains to plant growth rates, increased chances of algae incidence. Suggest using moonlighting/lower powered display lighting if extended lighting hours is desired for viewing purposes.
Having an adjustable light system gives flexibility. Changing the number of hours as well as intensity, by using dimmers or hanging kits, can change outcomes considerably. If you do not have plants that require high lighting, using lower amounts of light to achieve aquascaping goals is much more stable and require lower maintenance.
Power timers plug into standard power outlets and allow easy programming of when lights turn on/off.
For fish-only tanks with no plants - (5-7days) blackouts are an easy solution to get rid of algae. As algae do not have the larger starch storing structures of more advanced plants, they die off quickly without light.
Unfortunately, no... you can have plants that are visibly growing, and getting larger, but they can still be unhealthy or in a state of stress. They can grow but be nutrient deficient in cases where nutrient dosing is lacking, but more commonly unhealthy/stressed plants occur due to steep fluctuations in water parameters or nutrient dosing.
Plants will reprogram their enzymes to make the best use of current parameters. For example, if you suddenly allow CO2 levels to dip, plants will need to reprogram their internal structures to make do with the less available CO2 - devoting more proteins and energy to CO2 capture than say light capturing functions. The waste proteins are then ejected directly on the leaf/plant surfaces; this organic waste becomes the signalling mechanism for algae to spawn. The same thing happens when water parameters or nutrient availability fluctuates in a big way.
Robust plants can deal with such changes more easily (they are more adaptable) while some delicate plants that can survive in a narrow range of values will have faster deterioration of older leaves or melting. Thus, it is important to not only supply what is sufficient for plant growth needs, but to also to do it in a consistent manner over time. This is one of the reasons why it is recommended to do nutrient dosing a few times throughout the week, rather than in one large dose per week.
Take for example, both sets of Rotala macrandra below; they are both "growing", but the difference in state of health are apparent. Even ignoring color differences (which may be due to light or photography methods), observe the differences in - thickness of stem & leaves, internodal distance, state of growth tips, uneven leaf coloration vs even, full colored leaves. Weak plants are algae magnets.
Aquarists that try growing very difficult plants that have a narrow set of requirements will also face more algae issues down the road. If you are a beginner or new to planted tanks, choosing more robust species definitely makes life easier, and makes the tank more forgiving to fluctuations in parameters.
Ways to manage organic levels:
Never over-stock a tank in its early months. Livestock waste contributes significantly to algae issues in new tanks. (new meaning less than 3 months old).
Regular water changes (30-50% weekly).
Removal of old/decaying growth. This requires topping and replanting - cutting off and replanting the top portion of stem plants, while discarding the deteriorating bottoms.
Cutting off damaged leaves, and removal of floating debris.
Weekly/fortnightly light substrate vacuuming with turkey baster to remove surface debris.
Servicing clogged filters. Depending on your bio-load this could be done as frequently as every fortnight or up to every 3 months. Using a filter with an easy to remove pre-filter chamber that does not require dismantling of the whole filter is an easy way to make maintenance easy.
Water changes are not enough; good vacuuming techniques to remove detritus is important.
Steps to setting up a system that has effective bio-filtration:
Maintain high oxygen levels in the tank through sufficient gaseous exchange mechanisms. This is done by usage of surface skimmers and flow patterns that exchange surface layer of water with deeper layers in the tank. Higher oxygen levels is important for bacteria activity.
Using organic/soil-based substrates or appropriately sized sand (2-3mm) in the tank rather than inert large sized gravel. Increased porosity allows better bacteria colonization.
Having a decent filter and good flow to bring debris to the filter.
Filter flow rate of 5X to 10X of tank size. 1000L/hr filter on a 200L tank for example.
Shrimps, snails and other critters that breakdown larger sized organic particles.
Maintaining stable water parameters long term. This also means avoiding spikes of toxic elements (heavy metal content in water for example)
Pre-cycling the tank using starter bacteria cultures/products. Old school versions did not function well; the newer ones work.