The natural method

I think it is worth explaining again to our hobbyist friends what this way of running our beloved tanks consists of. Do not be scared, it is nothing out of this world; on the contrary, it is very simple.

The few rules to follow

I think it is common knowledge that there are few rules to follow for a tank to succeed:

1. Have a balanced Triad (Ca 400/420, KH 7-8, Mg 1350-1380);
2. Keep nutrients under control (for SPS tanks) in a range between 0.01 and 0.03;
3. Carry out 10% water changes every 15-20 days, with a well-balanced salt, to restore all the substances (mostly trace elements) taken up by the tank system.

1. 1Balanced Triad calcium, KH and magnesium
2. 2Nutrients under control the range for SPS tanks
3. 3Water changes with a well-balanced salt, to restore trace elements

Once these values are stable, there are few other rules to follow.

Starting from this base, there are few other rules to follow, because once these values are stable, no tank has problems. To keep things stable you also need good equipment, neither undersized nor oversized, so as not to allow any kind of imbalance, whether in excess or in deficit.

Equipment: light and skimmer

What do we mean by equipment?

Lighting (LEDs, combined with a few T5s, for those who want to keep SPS corals; T5s for LPS).

Depending on the light sources chosen (T5s are also perfectly fine for SPS), you need to match the right skimmer. I think it is common knowledge that LEDs have a greater oxidising power than T5s, so the choice of skimmer for our tank is closely linked to the lighting. Never pair an LED fixture with a powerful skimmer, because you would risk stripping the tank too much, leading to the gradual decline of our beloved SPS, which would find very few substances in the tank to synthesise what they need for growth and brightness.

Water movement

Water movement is also very important, because our closed system must have proper water circulation, first of all to help gas exchange, which not only removes excess CO2, helping pH to settle higher, but also stops debris building up on the bottom, a source of rising nitrates and phosphates, the main cause of our corals darkening and stopping growth.

1. 1Circulation pumps give the closed system proper circulation
2. 2Gas exchange excess CO2 escapes and pH settles higher
3. 3Debris kept moving on the bottom it turns into nitrates and phosphates
4. 4Corals nitrates and phosphates darken them and stop their growth

Water movement does two jobs: gas exchange at the top and no build-up on the bottom.

Pollutant spikes: act on light and skimming

Getting the balance right is not always easy, but by observing the tank, you find the right balance in everything.

If, for example, we came up against pollutant spikes, we could act either on the light sources or on the skimmer, or on a combination of the two. As we said, we could start by lowering our light fixtures by about ten centimetres towards the water surface, to let more light penetrate and so increase oxidation-reduction, while at the same time skimming wetter, so as to remove more quickly what has been oxidised. Or, on the contrary, we could skim drier and cut the photoperiod by an hour, letting the skimmer be more aggressive towards the pollutants in the water. All of this very calmly, combined with watching how the tank reacts, with the help of test kits. Changes of this kind should be observed over a month, because stripping the tank drastically could upset everything.

But believe me, it is not difficult.

1. 1Lower light fixture lowered towards the water surface
2. 2Wetter skimming removes oxidised matter faster
3. 3Shorter photoperiod one hour less light
4. 4Drier skimming skimmer more aggressive on pollutants

Act on the lights, the skimmer or both, without any drastic cut.

The bottles

If, on the other hand, we start playing with "bottles" (miracle products, according to those who make them) to speed up certain processes, we will only make things worse. Pumping the tank full of bacteria, just to give an example, will lead to a bacterial bloom, whose logical consequence is the bloom crashing, with the result of cloudy, milky water and corals receding and doomed to certain death.

The most common problems, without chemicals

Many complain of cyanobacteria outbreaks and, without even using test kits, use Chemiclean, which unbalances the whole system and which, unfortunately, we will notice too late... Instead, let's understand the cause and solve it naturally, perhaps with an extra water change, or by increasing water circulation in the infested areas, and you will see the problem solved. The same goes for filamentous algae: let's check the silicate level in the water, see whether our reverse osmosis unit is working properly, and we will solve this problem too. If we have problems with VALONIA algae, let's get some Mithrax crabs or a Naso vlamingii and they will be eliminated.

The same for flatworms: let's measure iron, and get the nudibranch Chelidonura varians or banana wrasses (Halichoeres chrysus) to get rid of them without resorting to chemicals.

Problem	What to do
Cyanobacteria	Find the cause; one extra water change or more circulation in the infested areas
Filamentous algae	Check silicates and make sure the RO unit is working properly
Valonia	Mithrax crabs or Naso vlamingii
Flatworms	Measure iron; Chelidonura varians or banana wrasses

First find the cause, then act without resorting to chemicals. These are the author's tips: see the note below.

Feeding the corals

There is no specific product for feeding corals; but in any tank, SPS or LPS, let's add small shoals of fish in proportion to the volume, and what they get rid of as waste will be enough to feed our corals.

1. 1Small shoals of fish in proportion to the volume
2. 2Waste what the fish get rid of
3. 3Corals feed on that waste, in SPS or LPS tanks

For the author no specific product is needed: fish waste feeds the corals.

Sources: [5]

These are the few rules to follow with the natural method: no secrets, money saved by not buying useless bottles, and excellent results.

Everything else is boredom...

Happy reefing, everyone

author: Pietro Romano

Sources

1. MolluscaBase eds., in WoRMS (2026). Chelidonura varians Eliot, 1903. World Register of Marine Species.
2. Froese R., Pauly D. (FishBase), in WoRMS (2026). Halichoeres chrysus Randall, 1981. World Register of Marine Species.
3. Froese R., Pauly D. (2026). Naso vlamingii (Valenciennes, 1835). FishBase.
4. Zamora-Silva A., Malaquias M.A.E. (2015). Diet preferences of the Aglajidae: a family of cephalaspidean gastropod predators on tropical and temperate shores. Journal of the Marine Biological Association of the United Kingdom 96: 1101-1112.
5. Burkepile D.E., Allgeier J.E., Shantz A.A., Pritchard C.E. et al. (2013). Nutrient supply from fishes facilitates macroalgae and suppresses corals in a Caribbean coral reef ecosystem. Scientific Reports 3: 1493.
6. Osinga R., Derksen-Hooijberg M., Wijgerde T., Verreth J.A.J. (2017). Interactive effects of oxygen, carbon dioxide and flow on photosynthesis and respiration in the scleractinian coral Galaxea fascicularis. Journal of Experimental Biology 220: 2236-2242.
7. Rosset S., Wiedenmann J., Reed A.J., D'Angelo C. (2017). Phosphate deficiency promotes coral bleaching and is reflected by the ultrastructure of symbiotic dinoflagellates. Marine Pollution Bulletin 118: 180-187.