The corals below were grown well outside conventional values:
Alk: 12 to 15 dkH (pushed to 20 without issue) Phos: 0.7+ ppm
Nitrate: 10+ ppm
People keep saying SPS can’t thrive outside natural seawater values. I’d counter that NSW is a default, not a requirement. It’s safe, forgiving, and asks the least of you in compensatory infrastructure, which is exactly why it’s the standard recommendation. But least demanding isn’t the same as necessary or what individuals want to strive for. The viable region is far wider and more multidimensional than a single setpoint lets on.
The thing people miss is that my values aren’t isolated rule-breaks, they’re a coherent package where each one licenses the others. I run a heavy SPS load under high flux and a 16 hour photoperiod, and that combination drives caloric demand hard. My system pulls close to 0.5 ppm of phosphate a day, so the 50+ grams of frozen food and constant throughput exist purely to keep phosphorus and nitrogen from becoming limiting reagents. What you read on a test kit is the surplus left after uptake, not a dirty tank, and it’s only a single frame. These values sit in constant flux, so a spot reading captures one moment of a moving system. Build out the full time series and it tells a very different story: the standing number rides on top of large, continuous turnover that takes a tremendous amount of input to sustain.
And those nutrients are doing real work. With phosphate abundant it stops being the bottleneck on energy metabolism, so biosynthesis and tissue pathways get to dominate. It can suppress calcification by adsorbing to nucleation sites, but I treat that as a deliberate trade, skeletal growth for other characteristics. On the nitrogen side, what I’m introducing isn’t nitrate as such, it’s a broad array of nitrogenous compounds, amino acids, proteins, particulate organics, lipids, coming from my foods and especially my CRT Concoction, which delivers a diverse, bioavailable spread of food and resources rather than a single inorganic ion. The test kit value is just the inorganic residual that surfaces after the corals have drawn from that richer menu. Together this is what lets me hold 12 to 20 dkH without burning tips. Run the same alkalinity in a ULNS tank and you’d get classic tip burn. So the high nutrients aren’t a liability I’m tolerating, they’re the mechanism that makes aggressive alk safe.
That’s the broader point about the numbers: they’re proxies. Bioavailability is what matters, and what a coral assimilates comes down to form and feeding, not the value on the kit. Viability is a property of the whole parameter vector holding together, not each reading’s distance from NSW.
This is the part I actually enjoy. Success isn’t one target, it’s a Pareto frontier. You can’t max growth, coloration, and polyp extension all at once, so I’d rather explore the whole gamut, find where the bottlenecks sit, and navigate to the end-state I want. Running six separate systems lets me actually do that. I can vary conditions across tanks, run things in parallel, and watch how differently they respond to the same change. Spend enough time manipulating variables and you come to appreciate how plastic these corals really are, how readily they adapt to a wide range of stable environments once they have the right resources: elemental ratios, nutrition, flow, light.
None of this refutes that NSW is safe. It refutes that NSW is necessary.
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