Coral Only Reef tanks

[Grey Guy]

I have kept a lot of coral propagation tanks (100 - 1k gallons), but always use at least 1 herbivore and something for aiptasia (usually raccoon or CBB). I'm not sure why everyone is jumping on the nutrient dosing bandwagon, either. IMO, it isn't necessary at all. Had 10 or so of these tables, some are 15+ years old with 2 fish in each, and the corals did just fine.

Thank you. Thanks for the nice photos too.

 

[Dkmoo]

I am totally flabbergasted. The last time I was here over 2 years ago, I don’t remember any talk about the necessity of phosphates and nitrates for coral growth. Now it is a big thing to be so concerned about. Is this just another passing trend or a major break through in coral care. When did this idea start? I know that plant life and algae thrive on nitrate but I don’t see how this applies to other living organisms. Is it the symbiotic bacteria in the coral that is now eating fish poop?
Maybe the human race will learn to do the same.

I don't think there's any major scientific break through. The science always supported the fact that corals need no3 and po4 b/c the N and P are necessary components to build proteins, enzymes, and coral tissue. What corals receive from Light is only sugars (C, H and O) via the zooxanthelle's photosynthesis, so it always needed to fund sources of N and P elsewhere to grow.

it's just that as the hobby progressed, we are making better use of the existing science. you have to keep in mind that when we say "NO3 and PO4" levels, we are not talking about the systems total levels - we are only measuring what's leftover in the water - after the corals/fish already absorbed what it needs.

A few years ago, the pendulum had swung really far into the "limit NO3/Po4" levels and where the whole concept of ULNS took off. But even in those systems, it was never about limiting nutrient input and starving the corals. it was about heavy in and heavy out, and to limit the excess remaining no3/po4 to minimize nuisance algae.

I think as the hobby progressed, people realized that, especially in established and mature systems, there's no direct correlation between the excess "remaining" no3/po4 levels and algae growth. Total nutrient input doesn't discriminate where it's going to - whether its coral or algae, so at the end it's simply a math game of relative surface area exposure to nutrient absorption. keeping a 0.5 ppm NO3 doesn't necessarily mean you'll be algae free - algae will grow when there's an opportunity to - ie when there's dying/rotting coral flesh, when you don't have enough grazers, or when you have immature "real estate" on your dry rocks where simpler forms of organisms like algaes are the first to colonize. otherwise, algae will never grow in nature b/c ocean's no3 concentration is a lot lower than what we keep in our tanks.

Realizing this, i think the hobby has started to swing back the pendulum from the "UNLS" extreme, into the more neutral range of it being OK to keep an acceptable level of no3/po4, and instead focusing on coral health, biodiversity, and natural competition as means of maturing the tank and algae control. This is why we have seen trends of dosing amino, phytoplanktons, better lighting, and generally more focus on stability and "pro coral health" measures becoming more popular.

 

[Grey Guy]

I don't think there's any major scientific break through. The science always supported the fact that corals need no3 and po4 b/c the N and P are necessary components to build proteins, enzymes, and coral tissue. What corals receive from Light is only sugars (C, H and O) via the zooxanthelle's photosynthesis, so it always needed to fund sources of N and P elsewhere to grow.

it's just that as the hobby progressed, we are making better use of the existing science. you have to keep in mind that when we say "NO3 and PO4" levels, we are not talking about the systems total levels - we are only measuring what's leftover in the water - after the corals/fish already absorbed what it needs.

A few years ago, the pendulum had swung really far into the "limit NO3/Po4" levels and where the whole concept of ULNS took off. But even in those systems, it was never about limiting nutrient input and starving the corals. it was about heavy in and heavy out, and to limit the excess remaining no3/po4 to minimize nuisance algae.

I think as the hobby progressed, people realized that, especially in established and mature systems, there's no direct correlation between the excess "remaining" no3/po4 levels and algae growth. Total nutrient input doesn't discriminate where it's going to - whether its coral or algae, so at the end it's simply a math game of relative surface area exposure to nutrient absorption. keeping a 0.5 ppm NO3 doesn't necessarily mean you'll be algae free - algae will grow when there's an opportunity to - ie when there's dying/rotting coral flesh, when you don't have enough grazers, or when you have immature "real estate" on your dry rocks where simpler forms of organisms like algaes are the first to colonize. otherwise, algae will never grow in nature b/c ocean's no3 concentration is a lot lower than what we keep in our tanks.

Realizing this, i think the hobby has started to swing back the pendulum from the "UNLS" extreme, into the more neutral range of it being OK to keep an acceptable level of no3/po4, and instead focusing on coral health, biodiversity, and natural competition as means of maturing the tank and algae control. This is why we have seen trends of dosing amino, phytoplanktons, better lighting, and generally more focus on stability and "pro coral health" measures becoming more popular.

Thank you for the detailed information.