"Just like the ocean!" That’s the gold standard we often hear in reef keeping, right? We meticulously chase natural seawater (NSW) parameters for salinity, calcium, alkalinity, magnesium, even pH. We want to recreate that pristine, natural environment for our corals and fish. But when it comes to nitrates and phosphates, are we truly mimicking the ocean, or are we actually heading in the opposite direction?
It's a bit of a reef keeping head-scratcher. We know the ocean has nitrates and phosphates, but our test kits often tell us to aim for zero in our tanks. Is this a contradiction? Are we missing something crucial about how nutrients behave in the vast ocean versus our closed-loop reef aquariums? In this blog, we’re going to navigate this nutrient conundrum and explore:
- Should we be aiming to match natural seawater nitrate and phosphate levels in our reef tanks?
- Did you know there are two main types of nitrates and phosphates in your aquarium – and only one shows up on most test kits?
- What’s the real difference between "organic" and "inorganic" nitrates and phosphates, and why does it matter for your reef?
Let's plunge into the depths of reef tank chemistry and clear up the confusion surrounding ocean parameters and those sometimes-pesky, sometimes-essential nutrients: nitrates and phosphates!
Chasing NSW Parameters – But What About Nutrients?
Many reef keepers diligently strive to replicate the major parameters of natural seawater. We invest in accurate refractometers for salinity, titration kits for alkalinity and calcium, and carefully monitor magnesium. This makes perfect sense – the ocean is the natural habitat of our corals, so mimicking its chemistry seems like a logical path to success.
However, the story gets a bit more complicated when we consider nitrates and phosphates. Typical natural seawater does contain detectable levels of both. But if you browse online forums or reef keeping guides, you'll often see recommendations to keep these nutrients "undetectable" or "as close to zero as possible."
So, which is it? Should we be copying ocean nutrient levels, or striving for something entirely different in our closed systems?
The Hidden Nutrients: Organic vs. Inorganic
Here's a key piece of the puzzle that often gets overlooked: there are actually two main forms of nitrates and phosphates in our reef tanks:
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Inorganic Nitrates and Phosphates: These are the forms that standard test kits measure. They are the end products of the nitrogen and phosphorus cycles – the simple, mineral forms that algae and plants readily consume. Think of them as the "tip of the iceberg" – the visible, measurable nutrients.
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Organic Nitrates and Phosphates: This is where things get interesting! Organic forms are bound up in living organisms and decaying organic matter – fish food, coral food, detritus, bacteria, etc. These forms are not typically measured by standard hobby test kits. Think of these as the "hidden mass" – the vast reservoir of nutrients that are present but not directly detected by our usual tests.
Imagine comparing it to sugar in your kitchen. Inorganic sugar is like the granulated sugar in the sugar bowl – easily measured and visible. Organic sugar is like the sugar inside a cake – it’s there, contributing to the sweetness and nutritional value, but you can't just scoop it out and measure it directly.
Ocean vs. Reef Tank – A Nutrient Disconnect?
In the vast ocean, organic nutrients are constantly being diluted and processed by a massive ecosystem. In our closed reef tanks, however, these organic forms can accumulate. We are constantly adding organic matter through feeding, and while our filtration systems work to break it down, some organic nitrates and phosphates will always be present.
This might explain why striving for "zero" inorganic nitrates and phosphates in a reef tank can sometimes be detrimental. We might be focusing so much on the measurable tip of the iceberg that we forget about the larger, unmeasurable organic nutrient pool.
Perhaps natural seawater has a certain level of total nitrates and phosphates (organic + inorganic) that is balanced, but the ratio of organic to inorganic forms is vastly different in our tanks compared to the open ocean.
Finding Our Own Reef Tank "Ocean" Balance
The takeaway? Simply chasing "natural seawater parameters" for nitrates and phosphates might be an oversimplification. Our reef tanks are not miniature oceans; they are unique, closed ecosystems with their own set of rules.
Instead of blindly mimicking ocean nutrient levels, perhaps we should focus on understanding the balance between organic and inorganic nutrients within our tanks, and striving for a healthy overall nutrient system that supports both coral and zooxanthellae health, without fueling excessive nuisance algae.
In the blogs ahead, we’ll explore practical ways to manage both organic and inorganic nutrients, and how to find that sweet spot for a truly thriving reef. Stay tuned, reefers, it’s time to think beyond just the test kit readings!
FAQs
Q: So, are organic nitrates and phosphates "bad"?
A: Not at all! Organic nitrates and phosphates are a natural part of a healthy reef tank ecosystem. They are part of the food web and nutrient cycling. The issue is when excessive organic buildup leads to imbalances.
Q: If my test kits read zero for nitrates and phosphates, am I still likely to have organic forms present?
A: Yes, very likely! Unless you have an incredibly sparsely stocked tank with minimal feeding and exceptionally strong organic waste removal, you will have organic nitrates and phosphates.
Q: How can I measure organic nitrates and phosphates?
A: Standard hobby test kits don't typically measure organic forms. More advanced lab testing can differentiate between organic and inorganic, but for most hobbyists, focusing on managing total nutrient load through good husbandry is key.
Q: What kind of filtration helps remove organic nutrients?
A: Protein skimmers are excellent at removing organic waste before it breaks down into inorganic nitrates and phosphates. Regular water changes also dilute both organic and inorganic forms. Managing detritus buildup is also crucial.
