0.75 mg phosphate corresponds to 75 mg of dry food (assuming Redfield ratios, which is probably a pretty good approximation considering a lot of aquarium food is based on plankton and low-trophic-level consumers), which is probably a pretty good pinch of food. But that's pretty much a baseless comparison since everyone feeds wildly different amounts and so we can't really say how that compares to the amount of food in any particular situation. It also certainly differs based on the brand of skimmer, how effective it is, how often it is is kept clean, and on and on through a massive list of variables that would need to be considered. One of the reasons that actual aquarium science that's broadly applicable can be hard to come by...
absolutely not. in fact i suggest feeding as much as you like. we setup our systems to collect nutrients not export. if we just change the way we setup the systems, then waste organic P is not an issue, and we can feed as much as the organisms we want to keep are used to.
Really? I wouldn't characterize a system with skimming, GFO, resins, etc together as designed to import rather than export. I feed what one would probably consider an appalling amount of food, because I know how effective my export mechanisms are, and haven't had a sign of phosphate. And not a vacuum in sight, because I prefer removing the P after the whole food chain has had a chance to use it.
the way we have our systems setup already starves the ecosystem. we are starving the bacteria used in decomposition due to the ever increasing amount of waste organic P. our little boxes of water just can not handle that amount of waste organic P, so people carbon dose. just get rid of the waste organic P. setup the system to export detritus as fast as possible. bigger skimmers. true settling tanks that are cleaned regularly.
Increasing amounts of P do not starve organisms. Period. Removing P before it can be recycled into the food chain starves organisms, so removing detrital P from a healthy tank will starve the system. Organisms at every trophic level need it. The key is keeping the soluble reactive phosphorus at acceptable levels, because that's what causes shifts in dominance from corals to algae, but that's why skimming and other removal methods are really necessary.
Carbon dosing does very little to remove P compared to other export methods because it removes it in Redfield proportion as organism export in a ratio of ~100:1 C
, and our systems are not well set up to remove the basal plankton and prokaryotes that are the primary utilizers of dosed carbon. We do agree on the importance of P removal, but it's not necessary (and possibly harmful) to focus on detrital removal rather than removal of dissolved organic P.
are you still growing in mass? at least in a healthy way?
no organism is 100% efficient. all of the material we bring in is not incorporated into our structure. the rest is discarded. if this were not the case then we would keep growing indefinitely. organisms are constantly moving material in and out of themselves.
Yes I am, but we don't like to talk about that...
I agree that organisms are incredibly inefficient (~20% on a good day), but their biomass is still concentrated nutrients. Remove 100g dry weight of algae (I just pulled that number out of thin air), and you've pulled out (roughly) a gram of phosphorus. Even if you're not pulling out every single molecule that passed through them, you're still pulling out the stuff itself, so there is a net reduction.
the more organisms there are, the more hamburgers there must be in order to support the biomass. that biomass is also producing a lot of waste material. something has to give. a system can not keep gaining in total mass and expect it to remain viable for long.
So our aquaria are not viable for very long.
Pretty much everyone's goal is for their corals or other occupants to grow, which is an increase in biomass. At a certain point, we start exporting that biomass e.g. through fragging, but in the simplest terms we WANT our biomass to increase. That waste material from one trophic level is food for another, all the way down into the microbial food web that keeps the system viable by recycling the necessary nutrients. Of course, at some point, an aquarium might reach steady state where the metabolic needs plus nutrient export equals the input, but I think for most healthy, growing aquaria, they are in a continual state of growth, ie. nutrient input.
ecosystem and diversity are just fancy words for phosphates sinks, which is a fancy word for cesspool.
Like it or not, our systems will always run on ecological principles. You can take the coral out of nature, but you can't take nature out of the coral. Not to mention that neither of those terms means what you say they mean. The ecosystem is simply the tank as a whole, and diversity is simply the number of organisms; neither is directly related to being a P sink. Diversity also has major positive impacts on nutrient (especially nitrogen) removal, as I've written about before. No one needs to be an ecologist to be a successful aquarist, but that doesn't mean we should be inaccurate in our use of the terms.
By your logic, everything that contains P is a sink (which, technically speaking, it is), which is a cesspool, so let's just get rid of all our organisms and call it a day. If we're going to use "sink" in the broadest way like that, we have to dismiss the notion that all sinks are bad. And technically a sink is a removal process, which is what we're after. Skimmers, GFO, resins, etc. are all sinks.
and how is that inorganic P being released into the water column if not from the decomposition of all of that waste organic P in the substrate? remove the waste organic P, and you remove the primary source of inorganic P. that is all i am saying. again GFO, resins, skimming are all going after the inorganic P in the water column. they must first wait for the inorganic P to get there from the decomposition of the waste organic P. they are a few steps behind the process.
That's exactly where it comes from. And it's a good thing, because like I said, every organism needs bio-available P to grow. Remove the P before it can be recycled, you risk starving the tank. The abiotic removal methods then pull out the excess that the organisms don't need.
This of course, begs the question: what about algae, which is usually the main reason people focus on P? Of course, this will also enhance algal growth, but that's why a healthy population of herbivores is essential in a natural system. We may not see much algae on the reef, but that's because the pressure from herbivores (like those schools of hundreds of surgeonfish) keep the standing level low. The zooxanthellae also need P, and recent research has shown that the corals do not provide sufficient levels on their own to support them completely.
are our systems like the ocean or not? if P is sunk in substrates in the ocean, then why would they also not sink in our aquariums?
I said earlier that substrates are a source of remineralized P, not a sink. There is P *burial* but that is not the same thing. Burial is removal from the system on everything except geological time scales (thus a sink). I highly doubt that we have burial in our systems with the exception of the few compounds that are refractory, and even then that's not technically true burial because our tanks do not experience sedimentation and something somehow, possibly, could theoretically come by and break it down.
we do not need to know what is accumulating in the substrates. all we need to know is that any biomass contains P. if there is an increase in total biomass of the system, then there is total increase in P. if that brownish gunk was not there when we put the substrate in, then why would seem like a good idea to keep in there now? that is all waste organic P. why are we wanting to keep poo as a pet? why is it that the reef hobby is the only livestock industry that believes keeping organisms in their own waste is a good idea.
If it's refractory, it's not really waste. Nothing can use it, and it's just inert molecules. The only truly problematic thing is when what accumulates is reactive, but nothing is eating it, which means there is a largely barren sand bed that has lost most of its function, which is very, very bad news especially in terms of nitrogen (and is probably one of the contributors to old tanks collapsing). The system is more nuanced than simply saying "all waste is bad" or all "P is bad". If it's not toxic, not harmful, and won't ever be recycled into the system, what harm is it? If you want to vacuum to remove it, by all means, though you risk destroying the infaunal population of the sediment if you're vacuuming the bed. But it's not necessary to do so.
that waste from the other organism can be a food for another organism, but like you said no organism is 100% efficient. it is also going to produce waste. what is feeding all of this biomass? there must be AVAILABLE food for ALL of these organisms in order to support them, if not then the population would remain steady or collapse. think about how many bacteria a worm would need to eat in order to survive. think about how many worms are needed to feed a fish. all of that extra food needs to be in play at all times in order to support all of that biomass. the lower the link in the chain the greater number needed to support the upper link. think hamburgers.
all biomass contains nutrients. if the total biomass of the system is increasing, then the total amount of nutrients is also increasing. they system is eutrophic. nutrient rich.
So is the reef. We do want growth.
This is exactly why I advocate heavy feeding coupled with aggressive export. You need the nutrients to support the whole system. Of course, not everyone wants a "whole ecosystem" tank complete with all the microcrustaceans, worms, etc. that make up those lower trophic levels, and that's perfectly fine. But if the natural system is what you want, we have to stop treating P like a nuisance and treat it like the necessary nutrient it is. Feed enough to provide it, establish a system that will keep it recycled and bio-available, and use multiple export mechanisms to keep the excess standing pool low.
Everyone loves hamburgers, but if you eat a lot of them, you're going to need to make sure you take the steps necessary to burn off the excess nutrients.
But if you don't eat anything, you're probably going to die.
