Dsb's work, what makes them work best?
- Thread starter barryhc
- Start date
The thing is Kris, that the "leaching" ( I hate that term ) begins deep ( or deeper ) in the bed. It is made soluble and released in the low pH envoronment. This is not at the surface of the bed.
At the surface of the bed what do we have? 8.3pH right? And what have we all learned about this, but that "binding" occurs best at this pH right? So now we understand why "clumping" occurs most often, at or near the surface ( by most accounts ), and why stirring, siphoning, and vacuuming, are potentially harmful, supported by the many accounts of trouble after maintanence.
So the released Phosphate has to get past this "binding barrier" at the surface of the bed, in order to get to the water column. And how did the phophate get past the binding barrier to enter the bed to begin with?
Well, bacteria of course, and how do we think it might get back out? Well, bacteria which are consumed by pods, which . . . . . . fish poop, and high flow to the skimmer ! ? *
Where have I heard this before? ? ? ? ? ? ? ? ? ? ?
Well now this brings us back to "the rest of the story"!!!!
To be continued . . . . .
Sorry Kris, the "Mass Belch" or release is only from extreme disturbance, so be "ginger" with that maintanence.
An OVERBURDENED sand bed will continue to take up phosphate until it is "full". It DOES NOT, then release it. It just can't process anymore, and since the bed is no longer reducing phosphate levels, they rise.
This condition will almost never occur in a reef tank, because the owner will be disgusted with algae and dead corals before it gets this far.
At some point they will usually either start over, switch to BB, or stop feeding like a pig farmer.
Does that help? > barryhc
I quite agree. I don't think much leaks out other than from disturbance, until it is too late, and the tank is already failing because of "overburden", and also as a result of over-predated infauna.
I would still use live rock, and even "seed the bed" just at the beginning. I sure do agree about controlling PO4.
I have reviewed that application a lot. A WHOLE LOT. I will probably include a "zone" in my 200 gal. setup, that operates just this way. I think it is really good for pod populations as well.
Good thinking on the PO4. > barryhc
OK Barry....I officially hate you. I just spent 20 minutes typing a response to Kris and you beat me.
You are right. Phosphates are continually being released in small amounts from a sandbed. The bioturbation that makes our sandbeds more efficient, also releases small amounts of phosphate from the pore water. Where do you find cyano and diatoms typically? The sandbed. Barry discussed how it happens chemically with aragonite. Since that is already covered, I'm going to discuss how it can happen with sands that don't naturally adsorb phosphates. In fact, it doesn't matter whether or not you are using silica, aragonite, pumice, etc. You will still have phosphates leaving the bed. Since only aragonite has adsorbed phosphates, why would that be? Because it's from the bacteria that's why. Weatherman had a formula on a now closed thread showing this process.
It's also happening in your LR. When we discuss sediments, we normally are thinking of sand or mud. However, to a bacterium, LR is sediment, hard coral skeletons are a sediment, etc. Take a look at the picture below. Where do you see algae? On the rock and in the sandbed. Part of this is because rough surfaces make it easier for an algal spore to attach but that is not as important as you would think. I could put a very rough (but not porous) object into an algae-ridden tank and there would be less algae that would grow on it because it wouldn't have an entire ecosystem of bacteria slowly feeding it phosphates.
The bacteria are basically a necessary evil. We want them for nitrification and denitrification but they have a side effect that we have to address. Sandbeds do slowly release phosphates but for the most part, they are still sunk in the bed and just cycle back and forth. Some of them will be in the bodies of infauna, some of them, will be in the bodies of the bacteria, some will be adsorbed to the sand (if aragonite), and some will be in the form of critter poop, and some will be in the water inside the bed.
OK....Knowing that MOST phosphates stay in your aquarium, here's my recipe for a succesful sandbed.
Only use RO/DI water in your tank
When you use carbon, soak it in RO/DI water to both deaerate and soak off any residual phosphates.
Don't overfeed nor overstock your tank with fish.
Soak all frozen foods in RO/DI water to remove phosphates
Have sufficient flow to remove as much waste as possible so that your sandbed doesn't have to process it.
I just spent 20 minutes typing a response to Kris and you beat me. You are right. Phosphates are continually being released in small amounts from a sandbed. The bioturbation that makes our sandbeds more efficient, also releases small amounts of phosphate from the pore water. Where do you find cyano and diatoms typically? The sandbed. Barry discussed how it happens chemically with aragonite. Since that is already covered, I'm going to discuss how it can happen with sands that don't naturally adsorb phosphates. In fact, it doesn't matter whether or not you are using silica, aragonite, pumice, etc. You will still have phosphates leaving the bed. Since only aragonite has adsorbed phosphates, why would that be? Because it's from the bacteria that's why. Weatherman had a formula on a now closed thread showing this process.
It's also happening in your LR. When we discuss sediments, we normally are thinking of sand or mud. However, to a bacterium, LR is sediment, hard coral skeletons are a sediment, etc. Take a look at the picture below. Where do you see algae? On the rock and in the sandbed. Part of this is because rough surfaces make it easier for an algal spore to attach but that is not as important as you would think. I could put a very rough (but not porous) object into an algae-ridden tank and there would be less algae that would grow on it because it wouldn't have an entire ecosystem of bacteria slowly feeding it phosphates.
The bacteria are basically a necessary evil. We want them for nitrification and denitrification but they have a side effect that we have to address. Sandbeds do slowly release phosphates but for the most part, they are still sunk in the bed and just cycle back and forth. Some of them will be in the bodies of infauna, some of them, will be in the bodies of the bacteria, some will be adsorbed to the sand (if aragonite), and some will be in the form of critter poop, and some will be in the water inside the bed.
OK....Knowing that MOST phosphates stay in your aquarium, here's my recipe for a succesful sandbed.
Only use RO/DI water in your tank
When you use carbon, soak it in RO/DI water to both deaerate and soak off any residual phosphates.
Don't overfeed nor overstock your tank with fish.
Soak all frozen foods in RO/DI water to remove phosphates
Have sufficient flow to remove as much waste as possible so that your sandbed doesn't have to process it.
Weatherman
New member
I did?
Nitrification:
106(CH2O)16(NH3)(H3PO4) + 138 O2 ------> 106 CO2 + 16 HNO3 + H3PO4 + 122 H2O
Denitrification:
106(CH2O)16(NH3)(H3PO4) + 94.4 HNO3 ------> 106 CO2 + 55.5 N2 + H3PO4 + 177 H2O
106(CH2O)16(NH3)(H3PO4) + 84.8 HNO3 ------> 106 CO2 + 42.4 N2 + 16 NH3 + H3PO4 + 148.4 H2O
By the way, there is evidence that phosphate is actually required for denitrification to occur. In the absence of sufficient phosphate, nitrate is converted back up into nitrite. I havenââ"šÂ¬Ã¢"žÂ¢t been able to find any specific references to phosphate limits to denitrification in marine environments, but hereââ"šÂ¬Ã¢"žÂ¢s an interesting study related to fresh water denitrification and the role phosphate plays:
http://www.ars.usda.gov/research/publications/Publications.htm?seq_no_115=128096
alten78
New member
Same here, have had my setup for better than a year with 10lbs LR/30lbs BR. I inadvertently went bb :hmm2: after I moved, its amazing how much junk has come off and keeps coming off the rocks. I only have two small clowns so i know i don't feed much...oh i want my sand back!
I don't have a po4 test kit and im afraid to even look, maybe i should use my new 75 for a fuge for my 29 :lol:
kbmdale
In Memoriam
So we know that one way to keep PH up is with light... Why not light the bottom pane of the fishtank in effect keeping PH up in the lower part of the DSB. If you keep your ph at 8.4 then the bonding shouldn't occur and the small quanity of po4 will get back in the water where it can be dealt with via the skimmmer.
Does that make sense.
It did when I thought it, but after typing it...lol...I'm not sure.
You are putting more of a demand on the bacteria in your LR when you are BB. That higher demand will be met by more shedding (which is caused by population growth). If you add a sandbed, the demand on the rock will go down and the shedding will still occur, just at lower rates. In effect, the detrital mulm will still be produced but it will be invisible because it will be in your sandbed.
<a href=showthread.php?s=&postid=6490655#post6490655 target=_blank>Originally posted</a> by Sindjin
Wow...
Great posts, everyone! I think we finally can say we understand PO4 in the tank...at least to a manageable extent!
The thing is... its relevant to a DSB or a BB so its a must-read for everyone. Or maybe Im the only one with the revelation.
I'm not sure I'm willing to say that we understand P in our tanks but you are quite correct. The husbandry that we should seek for both BB and DSB tanks is quite similar. Import as little P as possible and export as much P as possible. DSB's will hold onto P for you for a while but don't overburden it or you'll pay the price later on.
In fact, one of my main complaints about DSB's is that they give new hobbiests a false sense of security. Ask a new hobbiest if they are overfeeding and most will answer, "No." In reality, they likely are overfeeding but their DSB is masking their husbandry failures.
<a href=showthread.php?s=&postid=6490655#post6490655 target=_blank>Originally posted</a> by Sindjin
Wow...
Great posts, everyone! I think we finally can say we understand PO4 in the tank...at least to a manageable extent!
The thing is... its relevant to a DSB or a BB so its a must-read for everyone. Or maybe Im the only one with the revelation.
We're on an "upbeat" here, and Thanks Sindjin, for posting, especially this last one ! !
A-h-h-h . . . . BUT ( there he goes again with that "BUT poop" ), what about "THE REST OF THE STORY" ? ? ?
You remember the "STORY" don't you? It was the one that ended about where we are now, and then "teased" for someone else to finish, and then "To be continued" right ? ?
We have fairly well discussed the processes that occur from the surface of the sand bed, down to the "Aerobic-Anaerobic" ( or Oxic-Anoxic if you prefer to be "zone correct" vs "bacteria correct" ) interface.
Hope fully a few of you have picked up on the "Hypoxic" ( low oxygen ) terminology, and how this area of the sand bed is predominantly responsible for the beginning of denitrification, by way of the Non-Obligate ( Faculative ) Anaerobic bacteria that begin the reduction of nitrate, including the use of oxygen, phosphate and various other compounds in the process.
The point here is that this is the beginning of denitrification, and phosphate processing, and "sinking" and Hydrogen Sulfide production, and nitrogen gas "release, and Heavy Metals processing, and/or "sinking" etc. , and so you see that the "Story" is not finished.
Now I started to tell the "Story" if you will, and I left it unfinished, so that we could chew around on its beginning, for one thing, which we have all done very well, and thanks again Sindjin, for having said so, and having proclaimed that "NOW WE ARE THERE" ! ! !
So where are we? Well the Hypoxic zone is an interesting place in the sand bed, and it is a bit of a dividing line regarding oxygen of course, and bacterial processes, and the direction that the result of these processes is headed.
A funny thing that I have noticed, is that it also seems to be the dividing line in many peoples interest in the subject. ( No Curt, I am not poking at you here ! :lol: )
Now we know that Shimek, and Bomber, and Borneman, and many others have had a lot to say about these processes, but the result has turned out to be that the information available has been used as "spears" to be "chucked" from either side of an "endless debate".
We have witnessed the recent "meltdown" that was the result to a large degree of this "touchy subject" along with many other variables of course, and we certainly don't want to get back into that mess.
PLEASE, PLEASE, UNDERSTAND ME HERE ! !
I am specificly bringing this up in order NOT TO restart any of that mess here, but there is much valuable information available from these sources, and we simply cannot avoid references to that information, but we absolutely MUST NOT fall back into that mess, so I'm just asking every one ahead of time to be nice, like you are already doing.
Thank you all very very much ! ! ! ! !
So let's try to reference the information primarily here ( not the Authors ), and get on with the "rest of the story".
Now, the other reason that I did not finish "the story" is because it is here, that my own understanding of these processes becomes considerably less than "crystal clear", and I'm really pretty careful about what information I post.
And so, now I have been "caught" if you like, as I am sure, that many have suspected. I have been trying to gain a better understanding of these processes that are occuring below the Hypoxic zone, or "High-No" oxygen interface, since a long time before I started this thread and it is the specific reason that I started the thread.
I also am not complaining at all here about anyone having been off-topic here, YOU HAVE ALL BEEN REAL JEWELS in this respect, and I thank you all so much for it ! ! !
So let's finish the story, and Thanks to Weatherman for the recent formulas, now if I only knew what they meant ! !
Thanks All ! > barryhc
Weatherman
New member
First one is aerobic respiration, which is decompostion of Redfield Ratio organic material using oxygen. Results in carbon dioxide, nitrate, phosphate and water.
Second one is one path for denitrification, which is decomposition of Redfield Ratio organic material using nitrate. This is the one most of us are familar with. It results in carbon dioxide, nitrogen, phosphate and water.
The third equation is an alternate path for denitrification, common in eutrophic environments. It converts some of the nitrate back into ammonia.
There are, obviously, other denitrification paths as well. That reference study on denitrification of ground water revealed that in the absense of sufficient phosphate, nitrate can be converted to nitrite.
RichConley
New member
I may have already been beated on this, (i'm only about 1/2 way through the thread)
But, my take on cooking rock is this: Its not a solution, it merely is a delay tactic. Dont take that as me saying its bad, it just gives you a fresh start. Whether or not your tank crashes still comes down to whether or not you can export as much nutrients as you can put in. If you're putting in more then you're taking out, the cooked rock gives you some extra time.
If you're taking out more than you're putting in, you could probably put the nastiest rock on earth in there, and eventually it would be fine. In high flow/BB tanks, more detritus in general is being removed from the rocks, than is settling in the rocks.
As far as phosphate goes, Adenine Tri-phosphate is probably the most important chemical to cell respiration, so all that bacteria/etc in your skimmate is removed phosphate. All that worm spawn/critters/etc that you remove in your skimmate has phosphate in it, as well as nitrogen. Thats one thing that a lot of people dont seem to understand about the nitrogen cycle. It uses a lot of phosphate in the process.
It comes down to good design and husbandry, and of course, flow and skimming.
But ( hehehe ), wouldn't this mean that since Araganite is better at adsorption, that it would than retain more phosphate over a period of time, and that silica, since it is not adsorbing as well, would allow more phosphate to be processed in a different manner, including more "release back into the water column", at least initially?
I mean doesn't the Araganite act like a sponge, more so than the silica, and isn't this why some newbies, or others, get away with over-feeding for a while, and then the sponge fills up from this, and can't cover up the "indescretion" any longer?
And I like your recipe too, but I still have a lot of interest in substrates, and grain size. Maybe Bertoni, or someone else will show u pwit hsome good information here. I continue t obe concerned about "mud" sized particles.
While we're at it, I need a primer, on aDsorbed vs aBsorbed. "Weatherman"?
Thanks > barryhc
