Deep Sand Beds for Freshwater tanks

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I think trying to have anearobic gas in your tank is just a bad idea. I've lost fish to anaerobic gas through a canister filter, and it wipes out your whole tank.
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No offence intended bud, however I love these type of anecdotal horror story replies. It boggles me truly, as I dont even see how this is plausible - period!

Canisters are drawing decent volumes from an open aerobic environment into a tiny enclosure thats airtight o-ring sealed at best. Even with massive blockages due to not cleaning it, i still dont EVER see it reaching close to anaerobic or anoxic potentials. Besides the fact you'd smell it first hand, further more be able to test it, If by some freak chance it did do this, then my suggestion is to throw the unit away - cause clearly its not doing what its intended to by design - to pass volume though media.


Your not by definition trying to achieve anaerobic gasses ether! sulphate & sulfide production is due to the processes only. If your environment is healthy, with decent water column movement coupled an agitated surface layer ( and ....pref skimmed) for a decent gas exchange, then you've got nothing to worry about.

Looking at it chemically, H2S is solvable in water, however
A) its a slow transfer,
B) Dissolvability scale gradients are temp factored, meaning the higher the temp, the less solubility,(so consider most tanks hover between 25 - 30degC anyways) and
C) the reaction will create a weak acidic solution, which by ratio volumes anyways is negligible, however for those that are still worried, if your tank is buffered correctly to start with, isn't a problem regardless.

SW DSB's are populated by a whole wad of critters. Not disputing the fact the same numbering or even same ability can be said for FW beds, however i wouldn't look at this as a negative. Diffusion has always been the driving focus as a whole in regards to beds. As mentioned earlier anyways, freshwater animals exist that are happily to sift the top layers, & thats even before you bring the benefits of plants into the equation.

On the subject of plants (environment considerations of course) I personally believe that they are a significant complimenting tool also.
It all adds to the safety net of your system. Beds by surface area and assimilation, plants by growth and assimilation. Its a huge subject in its own right, so best left to another thread.

As ive said previously, I deploy them regardless. Benefits will always out weigh any negativism. And so far, have yet to experience any of the anecdotal problems that are plastered everywhere.

If anyone is concerned about it for your own application, stop sitting on your hands by reading and believing what others say & test for yourself. Research what you need to to familiarise yourself with the elements you can test for, then get to it! Who knows, you might find yourself having fun performing core samples for an attrition test.
 
No offense taken, the canister filter was a used one and the first canister filter I had used. The previous owner had left stagnant water in the impellor and I was too unfamiliar with canister's to know to clean the impellor area. I was just saying the gas is deadly. The fact still remains that even though you're not trying to acheive anaerobic gas, that is the side effect and I was merely stating I dont see the point in using this filtration method for freshwater because it is clearly not going to be as effective as it would be for saltwater. I'm no expert on the science behind this process, and I'm not spreading anecdotl horror stories. I'm just saying the theory behind dsb in saltwater is contigent on the micro organism's in the bed. Without them your just creating an accident waiting to happen. If a pocket of gas did form in your tank, which it probably will as thats what your trying to have happen, and you disturb it on accident your tank inhabitants are almost surely going to die. I'm totally for deep sand beds in saltwater tanks, and I think it's an interesting concept. But sandsifting animals just don't cut it, as in saltwater tanks many reasons dsb fail is because users do not get the correct grain size that facilitates micro organism growth, or they get a sandsifting animal that eats those organisms, and the bed fails. I merely pointed out the use of plants in this thread because if the goal is to lower nitrates, plants are a natural, and less dangerous way to accomplish that goal.
 
Always a good subject.

Myself personally, really dont see an issue with potential trace gas pockets hitting the water column.

Dont get me wrong, sour gas isn't safe by any stretch, it can potentially have significant health concerns for all involved, even us, however unless you have the worlds crappiest design, then i believe its a subject that perpetuates itself into a negative corner due to the infrequency of proper testing procedures.

Marine tanks total turn over is massively high compared to fresh water set-up by default, however unless your specificity catering for slow flow, most people that know what their doing should still have decent flow amounts.

So using the above, lets bring it into perspective..... its a gas, lighter than water so it rises exceptionally quickly. Bulk contact time & hence absorption time is in the bed. If anything, unless evolutionary specifics caters for it, it would swing more towards being detrimental for the sifters of any environment at anaerobic or anoxic contact level, rather than the act of any possible gas that's actually released.
 
carsona246;4484178; said:
Here is an excellent article that explains why I dont think dsb would be very effective in freshwater tanks. It's actually a pro dsb for saltwater, but if you read the article you'll understand why I'm a little skeptical about using dsb in freshwater.
http://www.ronshimek.com/deep_sand_beds.html
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Which part of that article makes you skeptical about using them for Freshwater? I just read the whole article and it all makes sense for me. I'd actually read it a few weeks ago. Even this quote from near the end of the article seems to contradict your previous concern about them:

Problems:
More imagined than real problems bedevil keepers of sand beds. The imagined problems are proposed by people who are ignorant of the sand bed dynamics. Among these imaginary problems are accumulations of hydrogen sulfide and detritus, and the need for sifting. Hydrogen sulfide will indeed be formed in the lowermost layers of a deep sand bed. It will NOT migrate up through the sediments to poison a tank. Hydrogen sulfide is an amazingly toxic gas, but that toxicity is exceeded by its pungent rotten-egg odor. The gas will have an exceptionally strong odor, and will seem overwhelming at levels well BELOW toxic amounts. If you can smell this stuff without it literally taking your breath away, it won't be at a harmful concentration. There is no real evidence to indicate that it may reach toxic levels in a deep sand bed.

Detritus build up in the sediment is another non-problem. If the sediment fauna is thriving, there will be a slight build up of fine detritus while the rest will be processed by the infauna. The final imaginary problem, the presumed need for sifting in a healthy sand bed, simply does not exist. Small organism movements "sift" the sand sufficiently. Any other sifting of a healthy bed will cause serious harm.
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Have you read the article presented by the Original Poster?

http://www.wetwebmedia.com/ca/volume_7/volume_7_1/dsb.html

It's a very similar writeup to the one you posted, except from a Freshwater DSB perspective. The saltwater critters that shift the sand are replaced by blackworms, planaria, malaysian trumpet snails, and plant roots. The Anaerobic and Anoxic layers are not disturbed enough to cause hydrogen sulfide poisoning in the tank.

Obviously you can't use this with fish or inverts that enjoy digging a lot, but those are only a small portion of the selection available to aquarists. You are also not going to be grabbing a broom handle and stirring everything up to release all of the hydrogen sulfide gas and kill your fish. It stays in the Anaerobic and Anoxic layers where it belongs.
 
Yeah, that was a good read and between the three or four articles I've read, I'm just about to make one and test it. And not on a snail tank this time.
 
I'm gonna be honest, I can't exactly understand what you're trying to say in that last paragraph. Gas is obviously lighter than water, but if a bubble of hydrogen sulfide was released in your tank it would be deadly. I'm not saying that anecdotl stories of hydrogen sulfide are a reason to stay away from concepts like a dsb, but it doesn't seem to make as much sense to me in freshwater due to the fact that your basically asking for hydrogen sulfide to form in your substrate. And regardless of flow, anarobic gas realeased into your tank will harm your fish. I'm not sure what your trying to say about "evolutionary specifics" but I still dont think dsb are a good idea for freshwater. I'm not saying it cannot be done, because I honestly dont know all of the factors or science that would go into a freshwater dsb, but it doesn't seem like a practical(or intelligent) option for the common hobbyist.
 
carsona246;4484367; said:
I'm gonna be honest, I can't exactly understand what you're trying to say in that last paragraph. Gas is obviously lighter than water, but if a bubble of hydrogen sulfide was released in your tank it would be deadly. I'm not saying that anecdotl stories of hydrogen sulfide are a reason to stay away from concepts like a dsb, but it doesn't seem to make as much sense to me in freshwater due to the fact that your basically asking for hydrogen sulfide to form in your substrate. And regardless of flow, anarobic gas realeased into your tank will harm your fish. I'm not sure what your trying to say about "evolutionary specifics" but I still dont think dsb are a good idea for freshwater. I'm not saying it cannot be done, because I honestly dont know all of the factors or science that would go into a freshwater dsb, but it doesn't seem like a practical(or intelligent) option for the common hobbyist.
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Basically he's saying that a bubble might escape occasionally, but it rises and is out of the water before anything bad happens. The bulk of the gas remains in the Anaerobic and Anoxic layers, and the organisms that live there are resistant to the toxic effects of it.

A single bubble is not going to kill the fish. heh. Even if there were a dozen bubbles a day, it isn't going to kill the fish. The anecdotal horror stories out there usually are the result of someone actually stirring up an untentional 'deep' section of their sand bed and releasing an enormous amount of hydrogen sulfide into their tank at one time. Similar to what you did with the canister filter. If you go in to it intentionally setting up a DSB, and know in advance that you are not supposed to stir it up, then there is no risk.
 
I was actually referring to the fact that the reason hydrogen sulfide would not poison a tank in saltwater is due to the prescence of microogranisms in a tank. Yes mts's, and blackworms may be able to replace the organisms used in saltwater, but I honestly doubt that you would be able to have them in such a large abundance.

I actually hadn't until after I posted, but I'm still not confident that using freshwater species would work as well as they aren't going to be as abundant, and personally my mts's dont really sift my sand all that well. Blackworms are an interesting idea, but I havn't heard of anyone trying them out so maybe theres something there.
"If the sediment fauna is thriving, there will be a slight build up of fine detritus while the rest will be processed by the infauna." is actually where I was going with the article, and why I'm still a bit skeptical about dsb's in freshwater tanks. Freshwater organisms that could fill this role are just too limited, and dont exactly "thrive"
 
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