Thanks for the elaborate response.
Couple of points, have had in tank DSB for the last 10 years and all my issues so far have been with nitrates and never with phosphates so if phosphates are as u say not treated i really fail to see how they were being dealt with, thats from my own experience.
what type of corals are in your system? softies do fantastically in a DSB bases system. SPS not so much without extensive resources used to counter the affects of P. Ca reactors, P reactors, bio-pellets, amped up salts. etc. the problem with P is that we are only able to test for inorganic P, and at level that is not really important to us. the test kits we have out can only read to about 0.01ppm. this is 10x less resolution than we need. we need to be testing in the 0.001ppm range to be of any use when keeping P sensitive organisms.
a chart showing typical ocean levels.
To answer some of ur points, the smaller grain sand thickness is needed to create a better anaerobic medium, larger layer on top will keep it from creating sand storm and allowing some types of microfauna that prefer it to live in it. Remember that softer sand was also better for some worms when sifting through it.
Not sure if total darkness is critical but in the last period when people where experimenting with RDSB, (remember an old mega thread RDSB in a bucket) people had better success i guess from the much added depth or maybe lower lights levels and linear flow on top. Unfortunately the benefits of RDSB werent tested long enough with the introduction of carbon dosing taking up the highlights, followed by BP.
an increase in microfauna is also a sign in total increase of P. whether or the P is testable is irrelevant. the amount of P is going up. in a DSB the bacteria and the microfauna that does live in there work at slowly migrating the P downward through the substrate. they are not moving the P upwards (if this were the way it worked, then substrates would be empty of life, nothing for them to eat). the more efficient the bacteria and microfauna are at moving the P downward the longer the substrate is going to last before showing the affects of P in the water column. the bacteria and the calcium carbonate are working together, by accident mind you, but this give and take of P between them causes the migration. the other organisms are just there as "bonus" i guess if you want to think of it that way. there is food they can eat, so they are there. the more food, the more organisms. as long as the population is growing all is good. it is only a big problem when a population crashes from either over population or runs out of food.
in total darkness, just allows the RDSB to act more like the deep ocean. algae is not able to get a hold in there.
Detritus or Poo will of course collect in the upper parts of an RDSB and some of it will be consumed by some detrivores and of course some will collect. This could have been partly the cause of the slow DSB failure we referred to as old tank Syndrome.
even if consumed by detrivores, the detrivores must poo also. as long as there is food going in, there is going to be more poo.
if you read up on the signs of eutrophication on natural reefs and how people describes what their tanks are going through when they say Old Tank Syndrome, they sound very similar.
RDSB would be the solution to that as you can restart it systematically at lets say 2-3 years and it'll be functional again in 6months.
absolutely. an RDSB is just another phosphate sink. using the calcium carbonate the same way as one would use GFO or the like. the only difference is that the RDSB is better at it. instead of just binding the inorganic P as in GFO and other P binders directly. the RDSB with all of the bacteria and other organisms binds both the inorganic P and binds even more P within the biomass. a much larger sponge. again there is nothing wrong with using a DSB, it is the way were told that it works that is the problem.
We agree at least that DSB and refugiums will take out at least nitrates. Phophate being very easy to deal with then how are fuges or RDSB a bad thing?
yes, nitrates can be converted to other nitrogenous compounds and can be off-gasses. though nitrates are not a concern for most of our organisms. nitrates just got the bad rap in the old school days because it was easy to test for. phosphates are the real problem. as long as detritus is removed in a timely manner, than phosphates are easy to deal with. the more they are allowed to collect either visibly or hidden in a substrate the more they will become a problem.
Carbon dosing or biopellets seem to also not handle phosphate as efficiently so would basically have the same limitation right? Again a phosphate reactor is so much easier and safer than a nitrate one
this gets into what bacteria need to do their "job". the same bacteria that are processing nitrates are also uptaking P. all organisms need P for energy. you can not have life without P. the same with N, H, and O, keeping it simple here. P reactors bind the inorganic P. carbon dosing gets the bacteria to do their "job" in the water column, then relies on the skimmer to actually remove the bacteria to remove the P. if there is not a strong skimmer, than the larger bacterial biomass can die, and rot, causing more P to be released. in most cases we can use N and P interchangeably.
I have honestly seen more crashes or losses from carbon dosing and biopellets than from a fuge or a DSB so regardless if im using a nitrate sponge or a method to reduce both nitrate or phosphate i still dont see how its such a bad thing nor how itl'll Cause my tank to crash.
this again goes with the way they deal with P. it is safer to use a P reactor than carbon dosing. the point is that the P reactor is getting its P a day late and a dollar short to the phosphate party. by the time the P is inorganic, it has already been broken down by the bacteria and what is left to get to the P reactor is any inorganic P that was not taken up by the calcium carbonate or other bacteria in the system. the more P binder needed, the more full the calcium carbonate P sinks are. the P reactor is masking the affects of eutrophication by taking out any extra available P being produced by the bacteria working on poo/detritus.
Agree that it will not be as fast acting as carbon dosing or a BP reactor but im sure itll have a share in nutrient reduction. Other advantages of fuges is acting like a breeding ground for pods which is a must for tanks heavy stocked with fish that rely on them.
pods are biomass. more signs that the system has available nutrients for them. is this a bad thing, completely up to the goal of the aquarist. if their must have organism only lives on pods, then absolutely, have a live sump (not a fan of the word refugium, i think a refugium is an area that is free of predation, but does not create a different trophic state). nitpicking sorry.
it would be just another large phosphate sink.
Back to the last statement on alga, we agree that it will consume nutrients right? Would be nice to see the chemical composition of alga which I'm sure will include PO4, and even if minimal, why is that a bad thing? Worst case we complement with GFO.
yes, algae does consume some nutrients. though like any organism it produces phosphate waste. we do the same. phosphate is not only used for a building material, but mainly as an energy source. it is constantly in motion. this is why it is important to view the total amount of P in a system and not what is showing up on the test kit. we need to use the living biomarkers to see the amount of P in the system. think of P as little energy bundles, they can never be destroyed. the more of these little bundles the more organisms that can use them. super simplification here. lets say a worm needs one P for energy, and it has 1 P inside it to keep it alive. that 1 P inside it can not just keep the worm alive. the P needs to be moving around. so the worm needs to eat 1 P in order to push the other P out. it is this constant movement of P that gives living organisms the energy to live. so if an organism is living, than it is converting P. the P is in motion. the P is not just sitting still. super simplification there, but it gets us close enough.
I see you have quite extensively proved your point (in alga or DSB not converting PO4) but i still dont see from your point of view what makes them bad and what causes them to crash a tank especially when you can trim your alga and restart your DSB.
animals are not able to do anything directly with freely available inorganic P. that is what plants/bacteria do. the more available inorganic P available the more algae/bacteria. if someone does not want a lot of algae, then they do not want a lot of available inorganic P. they need to remove the source of the P (poo/detritus) before it can become available to algae. if someone wants algae, then there is not a problem.
some corals on the other hand do not like available inorganic P. not sure how much you want to go into this part or not. to simplify again. taking SPS here, or for the most part any hermatypic (skeletal forming organism), they are symbiotic. the coral and the algae inside them trade those P bundles back and forth with the coral in charge, they have the mouth. when inorganic P is available in the water, then the algae inside the coral gets to be in charge. it does not need the waste products from the coral to feed itself, it is getting it through the water. this starves the corals of the real food it needs and also produces more O2 in the coral, poisoning the coral from inside. this is why corals brown, the algae is winning. so we up the lights, to produce more light blocking proteins to color up the corals. all are signs of eutrophication in the coral.
it really is amazing how involved P is in all of the different parts of keeping corals. this is why i say, following the phosphate trail is a deep rabbit hole that requires lots of popcorn and drink on hand.
G~
I had more difficulty with the scholarly papers.
