why do you think that PSB's are not doing much work in a reef tank? "cooking" LR shows that they are doing a significant amount of work in the system. all of that detritus building up while cooking is a visual indication that iP is being pulled from the calcium carbonate matrix. we know the cooking is done when the detrital accumulation stops. G~
as long as it is in solid form it can be removed. once removed it is not in play. if it is hiding in the substrate it is always in play. it takes time for decomposition to take place. it is not instantaneous. siphoning once a week will do wonders. you do not need to siphon every day. this is where the skimmer earns it keep. it is the only piece of equipment we use that actually exports P continuously. it makes sense to have the skimmer do as much as it can. have it see as much of the tank water as possible. G~
I've put these two statements together because they illustrate what I'm seeing as the disconnect here. Now, I can't say this for sure because as Amphiprion pointed out, no one's tested that stuff to see if it's even organic, but I've paid very close attention in my tank to where detritus builds up, where it seems to come from, and what happens to it over time. Everything I've seen has lead me to believe that that greyish crap that collects on the bottom of bare tanks, and in sumps and overflows is not material waiting to be broken down, but is actually produced by bacteria, and is what is left over after every possible usable atom has been removed. I've had a clump of the stuff in the first chamber of my sump for over 2 years. When I don't run filter socks, it grows a bit. When I do run filter socks (which is most of the time), it stays roughly the same size. That stuff also accumulates in the chamber I do water changes out of, which most of the time is downstream of a heavy duty filter sock and a protein skimmer. Not a piece of uneaten food has ever so much as entered that chamber, and yet a fine dusting of detritus will develop on the bottom between every water change. Bacteria, while small, are physical objects. Many hundreds of billions of bacteria can form biofilms. When bacteria in a biofilm die, usable molecules of their cells are used by the rest of the bacteria in the film, but bacteria, like all living things animals, produce waste that is not usable. I propose that this waste and the detritus you're talking about are one and the same. Bacteria make it, and you only see it when everything that could possibly be removed and reutilized is already taken out to the point where not even bacteria can break it down any more. I think it's a good idea to get it out for a bunch of different reasons, but saying that removing detritus will reduce the total amount of phosphate you'll need to deal with through other means, to me, sounds like saying you can keep the noise at a house party down by cleaning up the mess once the party is over. The noise was already made, and the phosphate was already released and and consumed.
Arguably either one of us could be proven wrong by a simple analysis of the detritus in the bottom of a tank. If it is the unusable waste product of bacterial metabolism and inorganic precipitates, your assertion that it is material waiting to be decomposed and therefore a potential source of phosphate is patently wrong. If it is undecomposed food and fish waste, I will eat my words an apologize.
you are correct. the point i am trying to make is that we are throwing large amounts of resources at our systems in order to keep iP levels down instead of just removing the waste organic material that ultimately leads to a significant amount of dissolved inorganic nutrients. we use GFO, algae, resins, carbon dosing to cover up the affects of the decomposition of the waste organic material. hoping to remove the iP from the water column at a rate that matches the dissolved iP of the environment we are trying to replicate. all of these are resources that would not need to be as necessary if the waste organic material was removed before it has a chance to decompose. yes iP is testable and gives us something to chase, but just looking to see the amount of biomass in the system can also tell you the amount of waste oP that is being produced and ultimately able to become dissolve iP.
No, we add resins, algae, skimmers, and carbon dosing to keep up with the rate we add nutrients to feed fish which are contained in volumes of water many trillions times smaller than the ocean. If you were to work out how many pounds of fish there are per gallons of water in the ocean, you'd probably find even the largest public aquarium is weighted several dozen orders of magnitude in favour of fish. Using algae, or resins, or GFO, or huge water changes, or excessive skimming, or sand beds or whatever, aren't "covering up" anything other than the fact that even 1 medium sized fish in an average aquarium will require enough food to rapidly turn that tank in to an uninhabitable slew without some system in place to deal with it's waste. Whether you have a tank with a sand bed or no sand bed, a fish will contribute inorganic nutrients to the water just through the act of exchanging materials across it's gills, at a rate vastly higher than can be "naturally" recycled or consumed in a small glass box. Hence water changes, live rock, skimmers, resins, carbon dosing, refugiums, deep sand beds, and in most cases, some combinations of many of those. Removing the sand bed will not change that, nor will it prevent decomposition from taking place in a million different nooks, crannies, and pore spaces in your rocks, nor will it make the amount of food your fish requires to survive go down.
You will have to add large quantities of phosphate every single day no matter what your system looks like to keep your animals alive, and running a BB tank will not magically make that problem go away, nor will it prevent phosphate from accumulating in the system and eventually the water column unless you put some system in place to deal with it. There are hundreds, probably thousands of people who run BB tanks and still require the use of GFO to keep phosphate levels acceptable for a reef. Perhaps your tank is able to maintain reasonable phosphate levels just through skimming and water changes alone, but such dynamics are highly dependent on a large number of factors that are specific to the way your system is set up in general, not just your lack of a sand bed.
You want less nutrients? Have less fish, or stop feeding the ones you have.
a BB dam would require less resources to hold back the water to maintain the desired water flow.
the dam would not need to be made as strong, the valves holding back the water would not have to be as large. these are all resources (cost/maintenance).
And foregoing the aesthetics of a sand bed while requiring more frequent water changes and manual cleaning of the bottom of your tank are not a cost incurred? Keeping with the analogy, what you save on damn construction costs you pay for in less available drinking water and reduced electrical output. There are trade-offs to every decision, but in this case you're saying that the trade-off for having a sand bed will be more difficulty maintaining low nutrients in the system over time, when there are literally thousands of people on this forum who are living testaments to the opposite.
it is important to know which type of reef someone is trying to emulate. the dissolved inorganic nutrient poor outer reef or the higher dissolved inorganic nutrient inner reefs. we need to setup our systems to match our must have organisms. why are we all told to setup our systems the same, when the organisms we keep can come from very different environments?
can we recreate the reefs even better if we would stop trying to setup all of our recreated reefs the same and start paying more attention to the environment that the organisms come from? if one wanted to grow sea grass, they would not use a BB system. if one wants to grow Acropora, then why have a substrate? i am just suggesting matching methodologies to the organisms wishing to be kept and understanding the pros and cons of each. that way the hobbyist can make informed decisions on what is more important to them and adjust for the pro's and con's to maintain the desired environment.
I have spent many hundreds of hours diving and snorkelling, from the Caribbean to Australia. One of my favourite places was Utila, off the coast of Honduras. I stayed at a hotel/dive outfit for two weeks with this amazing jetty that went about 100 feet out in the water. They built it because a solid wall of stag horn acropora about 20 feet from shore prevented you from accessing the 'outer' reef in anything but the highest tide, and even then your risked getting shredded. In low tide you could snorkel out from the beach to what looked like an artist's imagined rendering of the briar patch in coral, rising abruptly from glittering white sand in about 10 feet of water. The outer reef on the other hand, was dominated by massive sponges, tunicates, sea fans, and building size formations of porites, with nary an Acropora to be found.
Acropora grows where there is access to light, suitable substrate, the correct temperatures, and they don't get routinely pounded to bits by hurricanes. They can grow in the inner reef or the outer reef, and are adaptable to a wide range of depths. To make an 'inner' and 'outer' reef distinction is simplifying it beyond the point of being useful, as is saying that 'inner' reefs defacto have higher dissolved nutrients (they can, but being 'inner' is only part of the equation), or that tanks with sand beds are somehow a facsimile of said system just because of the sand bed.
agreed. i have been using the terms to denote the amount of dissolved inorganic nutrients available in the water column. i will be more specific from now on. it does lead to confusion.
But countless people with sand beds permanently maintain low dissolved nutrients in the water column...
