Correct Calculation of Daily Element Consumption in a Marine Aquarium

Calculating the daily consumption of various elements in a marine aquarium is a fundamental skill necessary for every aquarist. Without understanding this process, your system will constantly experience instability, which will ultimately lead to problems with corals and other inhabitants.

The essence of calculating daily consumption is quite simple: measure a parameter today, then measure it again after 24 hours and get the difference. For example, if the carbonate hardness was 8, and after a day it became 7, then the consumption was 1 unit per day. To obtain objective data, you should turn off the dosing of the corresponding element during the test.

However, this task, simple in theory, turns out to be much more complex in practice due to many interconnected factors that constantly influence the consumption of elements in the system.

Factors Affecting Element Consumption

Water Temperature

Temperature has an enormous impact on the speed of all biological processes in the aquarium. When the temperature rises by 2-3 degrees, all metabolic processes accelerate. Bacteria begin to multiply faster, corals grow more intensively and feed more actively. As a result, consumption of carbonate hardness, phosphates, nitrates, and other elements increases.

It's important to understand that the system doesn't react instantaneously. If the temperature fluctuated during the day by 1-2 degrees, it won't significantly affect the overall consumption. But if the temperature consistently remains elevated for a week or more, biological processes will reconfigure, and you'll see noticeable changes in element consumption.

The optimal temperature of about 23-27°C is considered the lower and upper comfortable limit for corals, at which they grow well and feed actively. At higher and lower temperatures, corals may experience stress, which reduces their growth and element consumption.

Feeding and Organic Additives

The second critically important factor is the feeding regime and types. When you feed the system, you're not just giving food to fish and corals, but also providing nutrients to bacteria.

If you start dosing carbon (for example, glycerin), bacteria receive an additional energy source, which accelerates their reproduction. They begin to process organic substances, nitrates, and phosphates faster. This in turn requires more carbonate hardness for biological processes, so you'll notice accelerated decline in carbonate hardness.

Food characteristics also matter. Some foods are rich in phosphates, others in nitrates. If you change the type of food, it can significantly affect the balance of elements in the system. For example, switching from a food containing phosphates to one without them can cause a sharp decrease in phosphate levels in water, which is especially dangerous if phosphate levels were already low.

An interesting nuance: even if food contains phosphates, it can ultimately lead to their reduction in water! This happens because along with phosphates, food often contains easily digestible carbohydrates, which stimulate the growth of bacteria that absorb phosphates faster than they come from the food.

pH and Oxygen Level

pH level is directly related to carbonate hardness and affects the rate of coral calcification. At low pH (below 8.2), many biological processes slow down. Corals grow more slowly, which means they consume less calcium and carbonates.

The oxygen level in water affects the efficiency of aerobic bacteria, which play a key role in the nitrogen cycle. Lack of oxygen can slow down nitrification and denitrification processes, which will affect the consumption of carbonate hardness and other elements.

Oxidation-Reduction Potential (ORP)

ORP is also an important indicator reflecting the amount of dissolved organics and oxygen in water. Low ORP often indicates excess organic substances and lack of oxygen, which can change the rate of biological processes and, consequently, the consumption of elements.

Biological Processes and Carbonate Hardness

Many aquarists are surprised when carbonate hardness suddenly drops without apparent reasons. It's important to understand that carbonate hardness is used not only by corals for skeleton building but also by bacteria for various biological processes, including denitrification.

When an active denitrification process (conversion of nitrates to nitrogen) occurs in a marine system, part of the water's carbonate hardness temporarily "disappears." It isn't consumed permanently, but rather "borrowed" for the process. In some cases, after intensive denitrification ends, you may notice carbonate hardness partially "returning."

This explains why sometimes, with stable dosing, you see fluctuations in carbonate hardness by 1-2 units. This is not a cause for concern if parameters return to the normal range.

Stability — Key to Success

The most important thing to take away from understanding daily element consumption is the critical importance of parameter stability. Corals and other organisms can adapt to various conditions, but they tolerate sudden changes very poorly.

Many successful aquarists maintain parameters far from ideal textbook values. But they achieve success thanks to the consistency of these parameters over a long period. Organisms adapt to stable conditions, even if these conditions deviate somewhat from the theoretically optimal ones.

Special Attention to Phosphates

Phosphates deserve special attention because their deficiency can quickly lead to coral death. Unlike elevated phosphate levels, which cause slow problems (such as algae growth), a sharp drop in phosphates to zero can cause coral bleaching and death in just one day.

We recommend maintaining phosphate levels around 0.07-0.15 ppm, especially in systems with active coral growth. This level provides the necessary reserve in case of temporary fluctuations or accelerated consumption.

If you use dosers to maintain phosphates, don't turn them off for consumption testing if the phosphate level is low (less than 0.1 ppm). In such a situation, phosphates can completely disappear in just a few hours, which will cause stress to corals even before the test is completed.

Practical Recommendations

1. During the first 2-3 weeks after setting up dosing, check parameters daily, recording them in the form of a graph. This will help you see trends and understand how stable your settings are.
2. Keep the temperature as stable as possible. Fluctuations within 1°C are acceptable, but not more.
3. Adhere to a strict feeding schedule and volume. Sudden changes in feeding regime can disrupt biological balance.
4. When making any changes (new corals, food changes, addition of growth stimulants), carefully monitor water parameters for at least a week.
5. Maintain sufficient oxygen levels through good water circulation and effective skimmer operation.
6. Don't chase "ideal" parameters. Stability is more important than absolute values within a reasonable range.
7. When using growth stimulants, always start with dosages lower than recommended and gradually increase them, tracking the marine system's reaction.
8. Pay particular attention to carbonate hardness and phosphates — these are parameters that can change most dynamically and critically affect coral health.

Understanding all these interrelationships will allow you not just to follow template recommendations, but to truly "feel" your aquarium, anticipating possible changes and responding to them before they lead to problems. By learning to correctly calculate and interpret daily element consumption, you'll take a big step toward creating a truly stable and thriving reef system.