Brief Overview of the Berlin System

Clarification and Additional Information About Calcium, Magnesium, and KH in Reef Tanks

1. The main purpose of my previous article was to highlight that these elements should not be overly focused on specific values. I have observed many beginners who keep SPS corals obsessing over stabilizing these numbers, while neglecting other factors. This is a serious misunderstanding. Of course, if you manage everything else perfectly, keeping calcium, magnesium, and KH within a reasonable range will certainly not harm your tank.
2. I confirm that my “aggressive increase” method works fine, but it may cause slight shock to the system. KH can also be increased aggressively, but I want to emphasize that fluctuations in these parameters are not the main cause of death in corals. However, if you have the time, I still recommend increasing them slowly. There’s a saying: stability trumps everything.
3. If you come across products that tell you how much to add per day, don’t blindly follow those instructions. Different tanks have different consumption rates. You can’t just add a specific amount of solution based on the volume of water. Without testing, don’t try to add randomly, as high levels could cause even bigger issues.
4. For LPS corals, which do not require much consideration for skeletal growth (and similarly for a small amount of SPS), most tanks do not need to add these three elements. Regular water changes are usually sufficient to maintain them well.

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The Berlin System – A New Perspective

Note: The following may be drastically different from popular thinking!

The Berlin System is something every reef keeper hears about when starting out. It sounds simple: live rock + lighting + water flow + protein skimmer (+ algae tank). You often expect it to “work wonders” when following advice from experienced reefers, but in reality, things are not that simple. What’s the problem?

In recent years, I’ve come to see the true power of the Berlin System. Looking back, I now realize that the mistakes I made were due to wrong initial assumptions.

Here’s my story: A few years ago, I thought that the best protein skimmer, the strongest lighting, and a large algae tank would solve everything. I used various additives, kept very few fish, and didn’t dare overfeed, thinking I was trying to reduce unnecessary nutrients. But slowly, I noticed the corals were losing color (SPS corals even started to look better), but they would keep dying. I would get new corals, and while they seemed okay at first, they would soon bleach and die.

Then, one day, I had an epiphany! I realized that corals need nutrition! I had been starving them! The bleaching process was the result of malnutrition! My previous approach was wrong!

I began researching. For example, Indonesia, the world’s largest source of coral, is located where the Indian and Pacific Oceans meet, right near the equator, where the water temperature and light are optimal for coral growth. The rich nutrients in the area sustain these coral reefs. Natural live rocks are full of small organisms, and the high density of life around coral reefs requires a lot of nutrients to sustain them. This confirmed that corals need nutrients, and pursuing extremely lean water was the wrong approach.

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How Does the Berlin System Actually Work?

I now understand the Berlin System as a “high input produces a biological chain.”

For example, nutrients from food (e.g., fish feed) are consumed by fish, some are dissolved, and after digestion, waste is excreted. Without a biological chain, these nutrients would pollute the water. However, with a complete biological chain, microscopic organisms can continue to consume the leftover nutrients, reducing pollution. This process continues: bacteria break down the waste, which is then absorbed by algae thanks to lighting. Many small organisms eat the algae, and bigger creatures eat the small ones. This cycle continues.

I often tell my friends: if you throw a dead pig into a swimming pool, the lack of a biological chain would lead to serious pollution. But if you throw it into a pond in the wild, due to the richness of the biological chain, the pollution is much less.

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Benefits of a Mature Berlin System:

1. Supports heavy feeding and high biological density, accommodating both soft and hard coral mixed tanks.
2. Requires fewer additional devices, resulting in lower setup costs.
3. Less reliance on bottled chemicals and additives, making it a more natural, worry-free setup.
4. High resistance to environmental fluctuations.
5. Promotes rapid growth of corals and other organisms.
6. Brings out vibrant, colorful corals (deep reds and greens).

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To fully understand how the Berlin system works, it can be a bit complicated, but if you want to play with a true Berlin system, here are some key ideas to keep in mind:

1. Live Rock is Key: The greatest benefit of live rock is that it’s “alive.” The microorganisms and biological chain it brings can help the tank mature quickly.
2. Don’t Worry About Your Live Rock: Even if your live rock isn’t thriving, it’s okay. Most corals come with a bit of base rock that brings some useful organisms along.
3. Avoid All Artificial or Dead Rocks: Regardless of what’s being advertised, these are not part of a true Berlin system. Even if you eventually grow live rock, why not just start with it? Of course, you can use some base rocks if needed.
4. Why Use Artificial Rocks in Some Cases?: There are two main reasons: 1) It’s a better choice for environmental protection because collecting live rock can harm coral reefs more than collecting coral. 2) Artificial rocks are sometimes used in non-coral tanks.

5. Don’t Worry About Small Critters: Many small crabs and bugs on live rock are beneficial, but some things, like garbage clams, hitchhiker snails, and mantis shrimp, may need to be removed because they breed quickly and have few natural predators.

6. Maturity is Key: The key to a successful system is the maturity of the biological chain. Don’t be afraid to feed your tank. Proper feeding helps speed up the system’s maturation.
7. Don’t Keep “Curing” the Tank for Too Long: Once the tank starts to green, it’s time to stop. The longer you “cure” the tank, the poorer the water becomes, starving many organisms.
8. You’re Not Just Caring for Fish and Corals: The real goal is to support the small creatures that keep the system alive. For example, using a flatworm treatment might not kill your fish or corals, but it will harm the system.
9. Berlin Systems Can Self-Repair: When problems arise, as long as the system stabilizes, the Berlin system will eventually repair itself.
10. Biological Chains Are Not Just About Adding Algae-Eating Snails: It’s about the unseen microorganisms that help keep the system running.
11. Protein Skimmers Don’t Need to Be Too Strong: Protein skimmers are only necessary when there’s excess pollution in the system. If the nutrients are low, you can even turn it off.
12. A Mature System Doesn’t Need Algae: The lack of algae doesn’t mean your tank is nutrient-poor; it likely means there are plenty of organisms eating algae. Conversely, if algae is abundant during tank maturation, it doesn’t necessarily indicate nutrient overload—it could mean the system lacks algae-eating organisms.