Are Deep Sand Beds, DSBs, dangerous to use in a marine aquarium?

[elegance coral]

So when it does, why can't GFO, organic carbon dosing, macroalgae, skimming, creature growth and other methods be suitable to export it before it rises to troubling levels?

Obviously that works as people with sand beds are able to keep phosphate adequately low.

We take steps to limit the accumulation of these harmful substances in our water. I'm just trying to point out that we're ignoring a huge portion of the equation by not limiting these same substances in the sediments (sand and rock) where we attempt to grow some of natures most delicate creatures.

We're debating the DSB's effect on the system. To do that, we need to look at what the DSB is doing. Not what the GFO, skimmer, or other devices and methods are doing. We can't give a DSB credit for something the skimmer is doing. If the DSB is adding unwanted substances to the water, but the skimmer and other methods are removing them, it doesn't change the fact that the DSB is adding them.

If we remove the organic matter in a timely manor, and not allow large quantities to accumulate and rot within our systems, our dependence on the methods you mention above is reduced. The system remains cleaner, and healthier, longer, without a six inch pile of rot and decay on the bottom of the tank.

 

[Fredfish]

Thanks for the clarification. So the question really is:
Do the critters in the DSB and the properties of the calcium carbonate structure process 100% of the waste/food (Y-Z) in my example, causing it to either increase the mass of the critters or be returned to the water supply for skimming/removal?

There really is no definitive answer to that until someone has the time energy money and patience to do experiments on the same scale as Toonen did.

I agree.

Couldn't sleep list night and read through this thread for about the 2nd or third time in the last week or so. My formal education is biology and math with a touch of physics and chemistry. But that was nearly 20 years ago and I never worked in those fields. This type of discussion is both intellectual and informative for hobbyists!

Nothing like a lively discussion on sandbeds to help put you to sleep late at night. :lol:

 

[Zalick]

T
Nothing like a lively discussion on sandbeds to help put you to sleep late at night. :lol:

It worked! :spin1:

 

[Fredfish]

...
You honestly believe there are bugs and worms lying on the forest floor just waiting for a leaf to fall from the sky so they can feed??????

When was the last time you went on a picnic? Ever notice what happens when you drop crumbs on the ground? You get a whole host of bugs show up and grab each and every crumb within an hour or so. Mouths just waiting for food.

Ever notice what happens to fruit that drops from a tree/bush/plant? If it is a soft fruit like strawberries will be gone in a day. Apples will take maybe three days. A whole host of critters will come along to take a bite or two. Lots of other critters will lay eggs and larvae will appear in short order (brand spanking new mouths). Bacteria will break down the rest and the nutrients released will be absorbed by the plants in the immediate area.

All this happens in temperate areas where organic accumulation is possible under the right conditions and over thousands of years. In the tropics, it's the same process increased exponentially. In the tropics there is no soil accumulation. Everything. Absolutely everything is consumed/absorbed/assimilated in very short order.

The bugs and worms on the forest floor live in a giant smorgasbord we call leaf litter. They need not concern themselves with the leaf that falls today.

First you are describing a temperate zone which is quite different from a tropical zone.

Second, leaf litter in North America is disappearing at a rapid rate. Why? The introduction of a single invasive species: the worm. Many forests already have no litter. At the course I regularly play golf at, last year's leaf litter is gone by mid August. So, even in a temperate climate, you can create conditions where there are mouths just waiting to be fed.

Food is a scarce resource. There are always mouths waiting to be fed.

I've also found DSB's seem to make the tank more resilient to some things...like coming home to find young kids have dumped entire (and rather large) cans of fish food in the tank, only to have the life in the sand bed assimilate it all with no bumps in nutrient levels. No more work involved, unless you move and need to break down your tanks.

Seems like a good reason to have that sand bed and all those critters. The more varied and dynamic your food web, the better able the tank is to absorb excess nutrients.

 

[GroktheCube]

As an aside, for those challenged by scientific terms (even when using them)...

SRP = Soluble Reactive Phosphate. This includes both reactive inorganic Phosphate and reactive organic phosphate. It has been found that there are some forms of organic phosphate that are reactive, as well as some forms of inorganic phosphate that aren't....hence the term SRP being better than just using inorganic phosphate

Given the impracticality of testing for organic phosphates for the average hobbyist, do you believe that plain ole orthophosphate tests are a decent proxy measure?

Granted, given personal experience I tend not to over value phosphate tests (within reason), but I'd still be curious to hear your opinion.

 

[billsreef]

The frustrating thing is when we get the same questions or points to rebut over and over, restated as if they are new, yet the answers are ignored, and the cycle repeated.

Sometimes it's amusing when you realize there are people telling professional marine biologists that our understanding of such things are flat out wrong

We're debating the DSB's effect on the system. To do that, we need to look at what the DSB is doing. Not what the GFO, skimmer, or other devices and methods are doing. We can't give a DSB credit for something the skimmer is doing. If the DSB is adding unwanted substances to the water, but the skimmer and other methods are removing them, it doesn't change the fact that the DSB is adding them.

No one has giving DSB's credit for skimmers and other filtration methods are doing. If you remove all those filtration methods and devices, the bare bottom tank will run into problems much sooner than the DSB one, IME...and yes, I've run tanks both ways. I've also dabbled with skimmerless DSB systems...great for growing lots of planktonic critters BTW, what is a DSB adding that hasn't already been added, and is also added to any other tank set up?

Given the impracticality of testing for organic phosphates for the average hobbyist, do you believe that plain ole orthophosphate tests are a decent proxy measure?

Granted, given personal experience I tend not to over value phosphate tests (within reason), but I'd still be curious to hear your opinion.

IMO, for hobbyist purposes, the commonly available orthophosphate kits are just fine.

 

[Fredfish]

Bill. Is there even value in measuring phosphate? My understanding is that it is never going to be a limiting nutrient in our systems.

I recall an experiment where they dumped nitrates into ocean water with something like .03 mg/l, an order of magnitude less than low levels in an aquarium, and they were able to generate algal blooms.

 

[Amphiprionocellaris]

Bill. Is there even value in measuring phosphate? My understanding is that it is never going to be a limiting nutrient in our systems.

I recall an experiment where they dumped nitrates into ocean water with something like .03 mg/l, an order of magnitude less than low levels in an aquarium, and they were able to generate algal blooms.

I think that's an interesting point. In the wild, nitrogen is considered the limiting nutrient (though in all honesty there is some debate whether that's universally true). Because nitrogen is really very easy to remove from the aquarium with a sand bed (or other methods of course), I strongly suspect that is also the case in captivity. That also fits with my observations of sporadic cyanobacteria patches in my system: cyano can fix their own nitrogen and so aren't held to the same limits and can grow when higher algae cannot. So really, in terms of green algal growth, nitrogen removal is more effective than phosphorus removal for control.

That is purely from a primary production standpoint; I think P might be more important when it comes to interactions with calcification. But that, and Randy can correct me if I am mistaken, is easily managed with GFO and their kin.

 

[billsreef]

Bill. Is there even value in measuring phosphate? My understanding is that it is never going to be a limiting nutrient in our systems.

I recall an experiment where they dumped nitrates into ocean water with something like .03 mg/l, an order of magnitude less than low levels in an aquarium, and they were able to generate algal blooms.

Only if it worries you The calcification issue that Tommy mentions is really the only reason I'd be concerned with P levels, and if your corals are actively growing and calcifying, you don't have problematic P levels

 

[Fredfish]

Whew! I was worried I wasn't worrying enough.

 

[billsreef]

Whew! I was worried I wasn't worrying enough.

That's alright, apparently I should have spent the last 20ish years worrying about tanks with DSB's crashing imminently :lol:

 

[Randy Holmes-Farley]

Bill. Is there even value in measuring phosphate? My understanding is that it is never going to be a limiting nutrient in our systems.

I recall an experiment where they dumped nitrates into ocean water with something like .03 mg/l, an order of magnitude less than low levels in an aquarium, and they were able to generate algal blooms.

That is not correct. All of nitrogen, phosphorus, and iron can be limiting in the ocean, depending on the circumstance, including the type of algae.

In reef tanks, one can easily demonstrate that phosphate can be reduced to levels where it is limiting for many types of algae. Folks using GFO to reduce algae demonstrate this every day.

This article shows N and P limitation of algae in the ocean:

https://web.archive.org/web/2004072...482/Kaneohe Bay algae N-P Larned Mar Biol.pdf

 

[Paul B]

Sometimes it's amusing when you realize there are people telling professional marine biologists that our understanding of such things are flat out wrong

LOL Bill, I do that all the time. That is because Marine Biologists and aquarists are different animals dealing in different envirnments. This is a hobby and quite different from Marine biology although the biology aspect may be the same. Aquarists deal with DSBs which are artifically constructed, lighting which is artificial, diverse, and regular not just the sun, controlled weather conditions, multitudes of creatures artificially brought together in a miniscule enclosure surrounded in most cases by fake seawater with added microorganisms that are not necessarily native to tropical seas.
Marine biologists deal with known sea conditions that are for the most part stable for that area and have evolved there unlike a tank that "evolved" in an afternoon.
I have a cousin who is a Marine Biology professor. He has never kept a tank of any type, not even goldfish. He had to SCUBA dive exactly once. When he looks in my tank he can name the worms and algae but has no idea what they do or how they got there or how to keep them alive. And he is a professor. I am sure he knows about whales and worms, how they think, what type of music they like and how they made their living, but he would have virtually no idea how to put salt water in a tank without spilling it all over the floor. It is not schooling in marine biology or any sciences that make a "hobbiest" a good or a bad hobbiest. It is a love of sea creatures and a determination to learn through "experience" how to keep these things alive and healthy for their intended lifespans under "artificial" conditions.
It doesn't matter if you have more degrees than a thermometer in marine biology, that does not make you an aquarist. That makes you a thermometer. :dance:

References:
Me
Martha Stewart
Pee Wee Herman
The guy on the corner

 

[billsreef]

Morning Paul :wavehand:

That is because Marine Biologists and aquarists are different animals dealing in different envirnments.

Your forgetting, the Marine Biologists in this thread are both Marine Biologists and Aquarists In this case, we are one and the same animal

Granted, some marine biologists are clueless about aquatic husbandry...aka aquarium keeping, but that doesn't invalidate the science.

 

[Paul B]

So I guess I am an electrician hobbiest and without electricians we wouldn't have reef tanks and would have to light and heat our tanks with whale oil (which I still do by the way) And Bill, I think bald people make better hobbiests.

Morning Bill. It must be nice there as it is raining here so my boating plans are cancelled. :wave:

 

[billsreef]

And Bill, I think bald people make better hobbiests.

We're in complete agreement on that :beer:

Morning Bill. It must be nice there as it is raining here so my boating plans are cancelled. :wave:

Sorry to hear that. We've got scattered showers. Still heading out, but have rain gear just in case we can't dodge the rain.

You'll get a laugh out of this...The other day I went offshore on an absolutely beautiful day. Mirror calm, clear blue sky, no rain expected till the typical afternoon showers. After collecting our Gulf Stream water, headed back in, got buzzed by Boarder Patrol, perfectly on time to make our dock by noon. As we approach the inlet, a squall appears out of nowhere, and right over campus where we are heading....It nailed us 10 minutes from the dock :lol: Cleared up after we tied up, and no more rain until the typical late afternoon shower

 

[elegance coral]

When was the last time you went on a picnic? Ever notice what happens when you drop crumbs on the ground? You get a whole host of bugs show up and grab each and every crumb within an hour or so. Mouths just waiting for food.

They were not just waiting for you to come along and drop crumbs from your PB&J.

Ever notice what happens to fruit that drops from a tree/bush/plant? If it is a soft fruit like strawberries will be gone in a day.

I live in central Florida. We grow strawberries here. We grow so many strawberries here that we have an annual strawberry festival just a few miles from my home. I've seen many strawberries rot. Never seen one completely rot away in a day. Not once. Never even heard of a strawberry rotting away in a days time.

A whole host of critters will come along to take a bite or two. Lots of other critters will lay eggs and larvae will appear in short order (brand spanking new mouths). Bacteria will break down the rest and the nutrients released will be absorbed by the plants in the immediate area.

So you understand the process. Great. Why then, would you come online, to a place where one of the major problems is plant growth, and support the process that fuels plant growth?

All this happens in temperate areas where organic accumulation is possible under the right conditions and over thousands of years. In the tropics, it's the same process increased exponentially. In the tropics there is no soil accumulation. Everything. Absolutely everything is consumed/absorbed/assimilated in very short order.

https://www.google.com/search?q=tro...a=X&ei=MfXcU4LiO5KWyATc64DoBg&ved=0CAgQ_AUoAQ

Just brows through the images in the link above.

First you are describing a temperate zone which is quite different from a tropical zone.

No...... The same processes take place in each location. The process is just sped up in the tropics. You still can not support large numbers of detritivores on the forest floor, or in a DSB, without large amounts of detritus. like I explained earlier, in areas where there is little rotting organic matter, you will have few organisms that feed on rotting organic matter.

Second, leaf litter in North America is disappearing at a rapid rate. Why? The introduction of a single invasive species: the worm. Many forests already have no litter. At the course I regularly play golf at, last year's leaf litter is gone by mid August. So, even in a temperate climate, you can create conditions where there are mouths just waiting to be fed.

No man!!!! What happens to the worms and other tiny critters when the leaf litter is gone???? They're gone too. You don't end up with a clean forest floor where the ground is crawling with large numbers of tiny critter just waiting for the leaf litter to return. When the leaf litter is gone, they die. They can not return until their food source returns.

Seems like a good reason to have that sand bed and all those critters. The more varied and dynamic your food web, the better able the tank is to absorb excess nutrients.

We run skimmers, change water, run GFO and GAC, dose carbon, and harvest algae, all in an effort to remove excess nutrients. Why do all these things if absorbing excess nutrients within the system is a good thing?

 

[tmz]

PO4 testing question.
FWIW,I test it often; just my habit . I test for inorganic phosphate. I don't think we have the ability in the hobby to test for SRP( soluble reactive phosphate/inorganic and organic) but PO4 tracking seems to be adequate for the 7 years or so I've been doing it.

Phosphate limiting does occur in some tanks per numerous anecdotal reports as Randy noted; particularly with aggressive use of GFO, lanthanum chloride or other removers. It often causes paling and in some reported cases death for calms and some corals. Phosphate is essential to life functions.

On the other hand ,phosphate in excess can alter the calcification process and perhaps throw off essential functions related to ATP;and, of course fuel nuisance organisms like algae and cyanobacteria.

IME, a PO4 level of 0.02ppm to 0.04ppm per the hanah 713 is adequate for the wide variety of corals I keep with very little nuisance algae .Some go lower ;some higher.Slow adjustments when made are better than precipitous drops or climbs,imo.

.005ppm , the seawater value for the upper reef waters ls not necessarily ideal as PO4 levels increase at depth significantly and some of the corals we keep live in water with higher levels .

Folks who pursue 0 PO4 and zero NO3 have reported nutrient deficiency issues ;sometimes addressed with supplements of various types . I've observed them in my tanks in the distant past when I was too aggressive in reducing PO4.

 

[tmz]

:strange:Where are the strawberries? Where is Humphrey Bogart( Cap'n Queeg of the USSS Caine)? He could find them and probably the missing phosphate too. Maybe we should all get a few large ball bearings and click them in our palms over the aquarium once in awhile. Being open minded,you can't say it wouldn't work.:spin1:

 

[GroktheCube]

I'm in the camp that remains unconvinced that even fairly high (within reason) phosphate levels are inherently problematic.

Some research shows a slight decrease in calcification rate by mass, but sometimes shows a slight increase by volume, or is sometimes equivocal. I don't think one can say with a high degree of certainty that SRP in and of itself substantially harms coral growth.

I'd love to see more (and rigorously controlled) experiments. Closed flow chambers preceded by strong UV sterilization, some GAC, and very fine mechanical filtration would be a good start. I'd be curious to see near zero PO4 vs .1 vs .5 vs 1 with algae and alelopathy removed from the equation, especially if P could be balanced against N.