Phosphate build up

[cwcross]

Ok, here is the next question.

Imagine we are back at the two flask system from before. In one flask, we have a bacteria infested sandbed ready to crash. In the other flask we have a nice pristine and sterile substrate. The ball valve connnecting the flasks is closed. No more phosphate can enter the system but other nutrients can, on an as needed basis only. There is mild circulation inside the flasks. What happens when we open the ball valve?

Regards...Collin

 

[Maxx]

No more phosphate can enter the system but other nutrients can, on an as needed basis only.

Are you talking like an active transport system?

There is mild circulation inside the flasks. What happens when we open the ball valve?

The selectively permeable membrane kinda throws this abit......I would assume that bacteria wouldnt be able to move through the membrane to gain access to the new clean flask,in real life. However since that would prolly kill the whole point of this question lets assume it wont keep bacteria in the flask ready to crash...just the phosphate. So what happens then is the bacteria begin to populate the new flask...but if P cant cross over and its necessary for life, it wont matter...cause the bacteria cant survive?
Assuming the bacteria can survive, the flask ready to crash has masssive hair algae growth, and and the other has a stable, but smaller bacterial population.
Nick

 

[cwcross]

No membrane, phosphate and everything else can flow freely from flask to flask

 

[Maxx]

Oh, in that case the bacteria will populate the flask, and the phosphate will bind to whatever sink has room. If the new flask has a stronger affinity for phosphate, it will pull the phosphate from the original flask.
Nick

 

[cwcross]

Oh, in that case the bacteria will populate the flask, and the phosphate will bind to whatever sink has room. If the new flask has a stronger affinity for phosphate, it will pull the phosphate from the original flask.
Nick

Yes, and what about the bacteria populations? Since the total population is limited by phosphate and there is more room in flask two, I would expect the bacteria to start slowly migrating into the second flask, and thus reduce the population over time in the 1st flask via competition for phosphate. Thus phosphate concentration, as measured by phosphate per unit weight of substrate, in flask one will drop in half, while that if flask two will rise to an equal level. Is this reasonable?

 

[Maxx]

I would say yes, the population should reach an equilibrium. I dont think it will raise too much, since there is no new organics being added, but total numbers (population), should remain fairly constant.
Nick

 

[cwcross]

If this is true then it may be possible to prevent a DSB from crashing by doing regular partial substrate changes. If phosphate is removed by taking a small section of substrate out and replacing it with new at some frequency, that provides a faster rate of export than phosphate is being added to the system, then total phosphate in the system should drop. It should then equilibrate at a reasonable level since a new export system would be added. I think the key factor here also is if bacteria can migrate faster than the rate that phosphate is added to the system can allow them to grow. I think this is likely the case since it can take years for a DSB to crash but bacteria can go through 10's of generations in a 24 hour period....C

 

[Craig Manoukian]

I hope this germain.

It is my understanding that bacteria populations will rise and fall depending on the bioload. Adding livestock increases the demand on the environment and bacteria will increase to accomodate. When the bioload capacity of he tank is exceeded then you are not able to add livestock. How does P fit into this situation?

As far as removing substrate, that is a strategy that is employed in this hobby. A quarter of the substrate four times per year as an example. The risk is that if you disturb a pocket of hydrogen sulfide then you can nuke your tank.

This is a great discussion, thanks for the opportnunity to chime in even though I'm highly unqualified to do so.

 

[cwcross]

I hope this germain.

It is my understanding that bacteria populations will rise and fall depending on the bioload. Adding livestock increases the demand on the environment and bacteria will increase to accomodate. When the bioload capacity of he tank is exceeded then you are not able to add livestock. How does P fit into this situation?

P fits because the fish/animals eat food, food has P, food/P is excreted by fish. The more fish, the more P you put into the system. P is only a single nutrient, however, but others are similar. However, phosphate is what algea loves so hence the problem. The more bioload, the faster your DSB will crash, other things being equal.

As far as removing substrate, that is a strategy that is employed in this hobby. A quarter of the substrate four times per year as an example. The risk is that if you disturb a pocket of hydrogen sulfide then you can nuke your tank.

Yes, this is why I believe the best place for a DSB is in the sump. We can isolate this area by turning off the pump. Manage the DSB and contain any damage. H2S is very volatile and can be sparged out of water with a good bubbler and air pump. No to very little substrate up top. Just MHO.

This is a great discussion, thanks for the opportnunity to chime in even though I'm highly unqualified to do so.

Its been fun. I think we are nearing the end unless we can extend the scope or have another idea/topic.

Sincerely...Collin

 

[Craig Manoukian]

Collin thanks so much for your time and explanations. How many cubic inches of remote sand bed would be required to support a gallon of water in the display tank?

 

[cwcross]

I Don't know the answer for that??? It depends upon porosity and the size of the grains. Rule of thumb is 2-4 inches but opinions vary. I would say more than 4 is a waste maybe. I use a mud based substrate and have about 3 inches in about 2/3rds of a 15 gallon sump with a 75 gallon main, with just about 1 inch course aragonite in the main, that I can vacume and stir pretty easily. This works well for me and I have about 80 lbs rock, 13 fish, about 15 types of corals, mainly LPS and softies, and never any nitrates and feed everyday. That being said, my system is only 8 months old. Not old enough to have any real problems yet with the sand bed.

 

[aquariumdebacle]

my sand-sifting gobies keep my 3-5 inch sandbed thoroughly stirred and in constant motion. i also only have two 40 watt bulbs and no corals. I feed flake and skim with a turbofloater. All my visible microfauna disappeared the first day I put the gobie in.

 

[Scooterman]

Ahh, Craig hit on my next question, In a system such as the BB, how much supplements LR does one need? We know the rule is anywhere from 1 to 2 lbs per gallon, well that has been that way for some time now, so what is a BB tank required, depending on Bio-load I know but is the ratio any different?

 

[cwcross]

Ahh, Craig hit on my next question, In a system such as the BB, how much supplements LR does one need? We know the rule is anywhere from 1 to 2 lbs per gallon, well that has been that way for some time now, so what is a BB tank required, depending on Bio-load I know but is the ratio any different?

I'm not sure there is any hard fast rule. It will depend upon how much bio-load you have in your system, what sort of rock you have etc. I would suggest that if your nitrates are staying very low that you have enough rock. If you are having problems with nitrates, you probably need more.

 

[Maxx]

....I would suggest that if your nitrates are staying very low that you have enough rock. If you are having problems with nitrates, you probably need more.

You could also add a clam....
Nick

 

[mojoreef]

Well, I'm sure you are right, however, I can imagine a lot.

Oh I hope you didnt take that wrong, bad wording.

I asked my microbiologist friend yesterday about limits on bacterial populations imposed by space. He said that yes, there certainly were limits. He then showed me some cultures he had growing that exhibited this phenomenon. According to him, when the cultures reach a limit for space in thier substrate, they will be pushed upwards into more oxygen rich environments in which they will die.

Lets take this and transpose it into our tanks and say a dsb. With the production of end product detritus and byproducts in a sediment bed the anaerobic regions will begin to fill and clog with products that can not be used. Since the limitations of area do play, the bottom and sides of the tank will put a limit on what the sediment can sink. The only regoin left to go, is up into the aerobic zone. This will eventually lead to that region going anaerobic also and the bed losing its ability to perform nitrification.

After that, phosphate will move from a regime 3 type behavior to a regime 1 type behavior and P and other nutrients will begin to build in the water column and also by saturating the limestone itself according to their equilibria. Here is where the aquariast will begin to notice more chronic problems that may indicate in impending system crash unless something is done.

I wouldnt say crash, more like it losses it abilty to filter and begins to export raw nutrients.

Yes, and what about the bacteria populations? Since the total population is limited by phosphate and there is more room in flask two, I would expect the bacteria to start slowly migrating into the second flask, and thus reduce the population over time in the 1st flask via competition for phosphate. Thus phosphate concentration, as measured by phosphate per unit weight of substrate, in flask one will drop in half, while that if flask two will rise to an equal level. Is this reasonable?

I dont think it would be that easy. the overloaded flask would migrate some bacteria which would bloom to meet the available food, but I would believe the vast majority would remain in the overloaded flask and basically cycle themselves out of existance.

If this is true then it may be possible to prevent a DSB from crashing by doing regular partial substrate changes.

Way to risky. With the bed in a constant state of flux through out it, you are running the risk of unleshing a ton of nutrients in various stages of reduction, also by the time you got to that point you would have a large population of Sulfate reducing bacteria, subjecting you precious critters to the chance of releasing that is really rolling the dice.

If phosphate is removed by taking a small section of substrate out and replacing it with new at some frequency, that provides a faster rate of export than phosphate is being added to the system, then total phosphate in the system should drop. It should then equilibrate at a reasonable level since a new export system would be added. I think the key factor here also is if bacteria can migrate faster than the rate that phosphate is added to the system can allow them to grow. I think this is likely the case since it can take years for a DSB to crash but bacteria can go through 10's of generations in a 24 hour period....C

Ok lets turn this around a tad. By taking out small sections of the DSB what is it that you are getting rid of?? (list the substances and what they are attached to).

Mike

 

[mojoreef]

Ahh the remote DSB theory. Some folks put this question to Dr. Ron and Rob T. They both seem to dismiss the notion as self defeating.
Lets look at this one for a second.
A sediment filter is only as good as the population of the correct bacteria that inhabits it. Its not a function of the size of the bed, but of the ammount of reducing bacteria it has. If a bed is not fed it will not have any bacteria (thats can be seen in real life on the sand that surrounds reefs, very few larger critters and very low bacteria populations), you basically just have an ammount of sand. So in order to keep a remote DSB functional as a filter it must be fed, now being remote it is going to be a whole lot less efficient then one that is in the tank itself. The though being that the in tank DSB will eventually get the vast ammount of the food it needs through food landing on it. In the remote unit, it will not get the same ammount, (its going to be hard to get all of it out and into the remote) but I guess with some tricky plumbing you might be able to get 60%?? not sure. Now the second problem is in contact time. In the tank contact time is not an issue (in most cases), but in a sump or remote you really need to slow the water down, so lets say 100 gph?? not sure but it would have to be really slow. So now how does that effect the ammount of bioload a remote could handle. I think mud systems fall into this catagory also.

just some thoughts.

Mike

 

[mojoreef]

Ahh, Craig hit on my next question, In a system such as the BB, how much supplements LR does one need? We know the rule is anywhere from 1 to 2 lbs per gallon, well that has been that way for some time now, so what is a BB tank required, depending on Bio-load I know but is the ratio any different?

Good question, thier isnt a ratio. To be honest you dont even really need LR. Let me explain. All of this disscussion is about export mechanisms. If any one mechanism was 100% effective you would need any of the others. Look at it like this Scott. The whole concept is to use 1, 2, 3 or a million methods AS required to deal with the removal of nutrients. The ammount of each and every one is dictated as per the effectiveness of the ones in use and the bioload they can handle. Wow, did I make that as complicated as I think?? lol
Example: I have a BB tank with a very low bioload and good flow and good skimmer, the effective rate of removal is 95%, I am done and dont need any other systems. OR I have a BB with a large bioload, my flow is good and my skimmer is great at removal, but I can ony achieve 75% of export, well then I need to look at another means of helping. So I have maany choices, Syphoning, LR, ozone, UV canister filter and so on and so on. Same concept is applied to all forms of export systems.
Here is the concept behind my tank. I have a large bioload, but very effective flow and a good skimmer. I figure I achieve about 75% export. I shyphon the tank for the little gather spots about every two weeks or as needed. This takes care of my particulate nutrient export, but does not address fully my dissolved nutrient problems. For me I use an ammount of LR (basically what I want in a look for the tank). this take a big chuck of the dissolve problem away and turns it into particulate (LR sheding solids) which I am really effective at removing. I have a carbon filter and an ozone set up but they stay dormant until required. In my case Ozone has come on about 3 times last year and carbon I use when I am syphoning.

hope that explained a little, lol I was havig a hard time with it.

Mike

 

[Scooterman]

Works for me, so If I'm lazy I need to keep a light bio-load, or add several removal equipment to accommodate. I know fish take part in a considerable amount of that bio-load but I don't have much info on the bio-load of corals, do they put out considerable amount on the BIO also, I'm thinking softies would the most? (this may need research on my part). Just wondering how they compare to fish in waste removal needs (new topic?)

 

[mojoreef]

Anthing that eats and poops really contributes (even the DSB). Corals out of evolution have become alot more effective at utilizing everythings available. Again the tissue rule applies. the more the tissue the most the waste, but the numbers are very low, low enough to really not put in the equation IMHO. Now other biproducts such as mucus, and slime do pertian a little

Mike