How Freshwater Deep Sand Beds Work

[Gammarus]

You need to look into making a career out of this somehow...

I don't PLAN on making a heavily stocked tank (I don't consider snails stock, 10,000 can live for months in a 5gallon bucket), Just a few shrimp, what ever DSB inverts I can find, and hopefully some beautiful plant growth. So for now, small grains should be fine. However, I may swap out for patio base sand, providing its aquarium safe. Its a very large grain, cheap sand. The sand that the LFS offer is all about the size of play sand, its just treated, or special in some way. And expensive.
I may add a sponge filter eventually. It would help with build up, and keep up the gentle circulation. I recall you mentioning usage of a small power filter.

I think of it as being trapped in a room with some one who's smoking, and the window is only cracked slightly. Its bearable, until his friends light up to. Then it builds up and chokes you all.

My LFS does not carry any live worms, nor do thier suppliers. I will be making a longer trip to another one to check at the end of the week.

Speaking of natural, have you seen these?

http://asia.cnet.com/i/r/2004/gb/biosphere_b1.jpg

Completely enclosed systems, only accessible through shattering. They last several years without food, or filter, just add light.
Shrimp, snails, algae, and micro life.
About what I'm aiming for.

 

[DeeDeeK]

You need to look into making a career out of this somehow...

...I may add a sponge filter eventually. It would help with build up, and keep up the gentle circulation. I recall you mentioning usage of a small power filter.

I think of it as being trapped in a room with some one who's smoking, and the window is only cracked slightly. Its bearable, until his friends light up to. Then it builds up and chokes you all.

... Speaking of natural, have you seen these?

http://asia.cnet.com/i/r/2004/gb/biosphere_b1.jpg

Completely enclosed systems, only accessible through shattering...

The analogy of the room with the cracked-open window and smokers is great!

I use a souped-down power filter. I actually had been using a modified Whisper - styled internal filter but needed a filter for the 5 gallon DSB shrimp tank so I moved it and reinstalled the built-in overhead filter in the hood of the fish tank (my "big" tank, at 9 gallons) and throttled it back by perforating a bit of plastic bag and sticking into a part of the filter's plumbing. The powerhead in that filter is rated for 685 liters per hour (about 180 gallons, or 20x the tank's volume/hr!!!) because the tank was intended to be a nanoreef setup. The media is a mixture of open-cell plastic kitchen sponges and some filter floss. I do a lot of "gardening" and need to have some decent mech filtration because of the superfine mulm that comes puffing out of the sand when I'm farting around with the plants. I just don't have the patience to wait for it to settle out.

Oh, I have set up the overhead so it actually doesn't splash either internally or where it pours back into the water.

Yeah, well, I actually live in one of those glass biospheres. You see, I am actually a dwarf shrimp. There. I said it. I'm an arthropod.

I'm actually wanting to make a career out of this. I'm designing some nano-sized aquaria which a partner and I will build and then establish freshwater DSBs in and sell to "upscale" clients like law offices - to put on the receptionist's desk sort of thing, with service contracts for maintenance.

I'd REALLY like to get the $$ together to set up a bunch of DSB tanks to experiment on and to get the equipment to take good measurements with. Then I'd like to write a book with two parts: one part would be very practical, a guide to deciding what your aims are (like how you'd like to stock the tank, is it a display tank, an aquascape, invertebrate tank, etc.) and implementing the sort of freshwater DSB which will best support your goals; the second part would be an examination of the DSB in detail, written in that sort of educated layperson's science-writing style they use in Scientific American magazine.

Anybody care to invest?

 

[Anoxia]

I just want to say something about particle size. I have clay under my sand, and it doesn't seem to be hindering the denitrification process, because the nitrates stay at 10 or so (my test doesn't go under 20, so I have to guess by the shade of pink) no matter what. Maybe they would be even less without the clay?

I just think that mud is a very common and natural thing at the bottom of a freshwater pond or stream, so how could it do any harm to have particle size that small? The only thing I've noticed is that the clay layer doesn't turn as dark as the sand layer, though I don't know what that means. It seems like that layer would be more dense than the sand layer, but it isn't, and I think the plant's roots are able to penetrate it just fine.

Maybe having a smaller particle size just means you don't need such a deep layer for denitrification. One of the reasons I added it was because I read a paper (that I can't find now) saying that the reason they thought DSB would be unsucessful in freshwater was because you would either need a ridiculously deep sand layer, or an extremely small particle size, and they felt it would be impossible to find a particle size small enough, so I told myself small particles = a good thing.

The only place where I have found much mention of the use of clay since then has been the koi keeping forum, where they now use baskets of clay kitty litter mixed with laterite for anoxic filtration, and the really serious competitors raise their show fish in "mudponds" that have clay bottoms, because the fish grow faster and larger, and have better colors that way. They think it's because the suspended particles encourage the growth of micro life in the pond. I haven't had much suspended particles because of the sand cap, unless for some reason I dig stuff up. Anyways, my point was that small clay particles seem to be just fine, even though I can't tell you why.

 

[LeahK]

I've been reading through this thread and through some of DeeDeeK's other threads on blackworms, and I'm hooked. I really like the idea of a DSB and "live sand."

I have a question for you, DeeDeeK: What's the relationship between maintaining the DSB and cutting back on water changes?

I read on your other blackworm thread that you do a water change of 15% once per month. Now, I know myself, and I can't deal with cutting back on water changes :grinno:
It's not that I doubt that your tank, and that Walstad-type tanks, achieve some sort of balance that drastically reduces the need for water changes. It's just that I still like the idea of fresh water.... even if it's not strictly necessary.

So I guess my question is, also, will frequent water changes disrupt the balance that the DSB promotes?

There seem to be two ways to successfully maintain a tank: 1) the conventional way usually recommended here on AC--vacuum your gravel and change 30% to 50% of your water once per week; and 2) establish a DSB-type ecosystem. People who take option 2 also cut back on their water changes.

But I'm wondering if I can have the DSB and the water changes, too. Let's say that I want to do a water change of 50% per week. And let's say that I will just change water and not vacuum the gravel. Do you think I would still be able to have a functioning DSB?

 

[DeeDeeK]

First let me address Anoxia: Hmmmmm.....You have a very good point there. Experiments must be performed and measurements taken! Plenty of times I take a few semi-subjective observations, a little book-knowledge, some logic, and my own personal bias in favor of whatever result I'm seeking and I end up writing that such-and-such a thing works such-and-such a way for such-and-such reasons as if I really knew what was going on.

Honestly, it's refreshing when somebody else chimes in with some astute, contradictory OR complementary observations or reasoning!

So yeah, clay. Or soil in the case of Diana Waltstad.

So, then, what of the idea that too fine a sand can be a bad thing? Maybe very fine sand works OK but the finer the sand, the shallower the bed must be?

I think the way this sorta stuff works is that as you change one variable (sand grain size distribution), other variables (behavior of diffusing solutes and infiltrating solids) change in response, requiring one to adjust a third group of variables (such as sand bed or heterogenous bed depth, stock levels, filtration) in order to achieve the desired outcome (such as a healthy tank with fish, crustacea, and plants, low algae, low maintenance, and smells good). Rather than there being hard and fast rules about sand, feeding, livestock levels, filtration, water changes, etc., there in reality is a set of relationships between different elements of the system. The broader and deeper our understanding of those elements and their relationships, the more flexible we can be in implementing our aquaria.

So, what I advocate when I advocate the freshwater DSB is an approach, somewhat narrow in scope, to setting up an aquarium with a sand substrate. Anoxia, your suggestions are the sort of change of variable (substrate composition) which then suggests another change (depth of substrate) to achieve denitrification!

My guess from what I've experienced and read about was that clay wouldn't be so good but now we are informed about koi ponds with clay bottoms and their benefits! You know, I like to be right but I love to be wrong when the truth is so much more interesting than what I'd believed! Just think how satisfying it'll be to whip out that bit o'knowledge and impress our friends who haven't been clued in yet about clay and tiny particles and biofiltration.

I have a question for you, DeeDeeK: What's the relationship between maintaining the DSB and cutting back on water changes?

So I guess my question is, also, will frequent water changes disrupt the balance that the DSB promotes?

Good questions. The answer to the first one is sorta simple. When you maintain a robust DSB which can exchange chemicals between itself and the water column rapidly (due to the DSB's excellent openness to diffusion), there will be a large population of bacteria within the sand which eat organic molecules - proteins, sugars, amino acids, fatty acids, oils, alcohols, humic substances, etc - especially those molecules which are dissolved and therefore transported via diffusion through the sand bed. Those organic molecules, along with dissolved gasses like H2S, NH3/NH4, CH4, etc., are what foul the water. OK, this is a somewhat incoherent paragraph (my roommate is watching cartoons very loudly in the background right now and I can't think!!!!)but what I'm trying to say is the DSB serves as a biofilter which not only nitrifies and denitrifies, but also consumes organic contaminants common to decay, eats H2S, methane, and other crud. SO, we have not only lower levels of nitrate (and of course 0 NH3/NH4 and 0 NO2) but overall cleaner water.

Sorta simple. Yeah. But I didn't sleep all last night so I'm a tad incoherent.

Question #2, will frequent water changes upset the balance? Well, not in my experience - which is limited. I've had periods where I've changed much more water and on a weekly basis and didn't notice any special differences between the weekly and the monthly schedules. I can't think of a reason theoretically, why it should interfere. Doesn't mean it won't interfere, just that I can't reason out why it might.

Though the freshwater DSB lends itself to low-tech and generally crunchy granola philosophical approaches to the aquarium hobby, there's no reason not to incorporate it into any practice or approach it may fit into. High tech with a DSB, ultra-brite lighting, CO2 injection, fert dosing, etc., is just as valid as a el Naturalé style DSB tank. As long as the practices you incorporate work towards a result you desire, there's no reason to be dogmatic.

G'head! Change all the dang water you want for as long as it works for you! You might like the DSB because it makes for good planting, especially once it's begun to mature. Or because you want a sand substrate that looks good but doesn't require you to hand-stir it up once a week to avoid bizarro toxic bubbles. Or because you want a bunch of worms on hand in the substrate to feed your fish with. Or whatever as long as you want it and the DSB supports it.

 

[Gammarus]

COINCIDENTALLY, I have evidence in support of smaller grains in shallower beds.

My triop died last night of old age and I began the process of breaking down her aquarium and portioning out the sand for drying, to hatch her eggs later. Her sand bed was slightly less than an inch. It was also play sand.

All of it was gray, except for the very top few mm of sand. But it was a light gray. She lived about two months, had 2 other triops for about half of that time, and a hand full of snails in a 5 gallon aquarium with about 4-5 inches of water.

The VERY bottom layer of sand was slightly darker. None of it smelled bad at all, just a very faint earthy smell, like, well, wet sand and dirt. Which is good because its drying on a shelf right now and that toxic smell it could have had would make this room horrendous. She never got a water change, just top offs, and was fed several times a day. Her water was crystal clear.
I'm sure the triops obsessive digging contributed to it somehow.

Im going to start 2-3 batches. Use some for breeding in the 5g again, and put several into the 20g DSB aquarium. They dig like they are trying to find oil. But only go down 1-2 inches, and seems like they fill their hole back in when done. I'm only going to try a few, because they will browse on plants if they get hungry enough, but the damage is VERY minimal. But then I kept mine well fed to. I think they will be a fine addition to the sand bed.

 

[DeeDeeK]

COINCIDENTALLY, I have evidence in support of smaller grains in shallower beds.

Her sand bed was slightly less than an inch. It was also play sand.

All of it was gray, except for the very top few mm of sand. But it was a light gray.

The VERY bottom layer of sand was slightly darker. None of it smelled bad at all, just a very faint earthy smell, like, well, wet sand and dirt. Which is good because its drying on a shelf right now and that toxic smell it could have had would make this room horrendous. She never got a water change, just top offs, and was fed several times a day. Her water was crystal clear.
I'm sure the triops obsessive digging contributed to it somehow.

They dig like they are trying to find oil. But only go down 1-2 inches, and seems like they fill their hole back in when done. I'm only going to try a few, because they will browse on plants if they get hungry enough, but the damage is VERY minimal. But then I kept mine well fed to. I think they will be a fine addition to the sand bed.

Hmmmmm.....This is all very interesting! Perhaps one way to look at it is not in terms of sand, gravel, soil, clay, etc., but a continuum of substrate grain sizes and other characteristics, all effecting the diffusion of dissolved gasses and nutrients and the infiltration of decaying solids into the bed. As the "sand" bed media changes from coarse to fine and diffusion and infiltration slow, depths of the aerobic, anaerobic, and anoxic zones diminish and available surface area for bacterial colonies expands drastically.

Triops, eh? Very paleozoic!

But back to the substrate. You got me thinking. How about two drastically different grain sizes like one range of ~.5mm to ~1mm and a smaller quantity of one with a range of whatever size your average pottery clay's particles are. The smaller particle comes in a small enough volume that it doesn't completely fill the interstices of the larger particles. Then you'd get really rapid movement through the "sand" bed but some of the incredible surface area that material like clay provides.

Anyhow, this just convinces me further that the most powerful and flexible way of approaching an aquarium set-up is by knowing the function and relationships of the things one is putting into it as relates to one's goals for the tank. A freshwater SHALLOW Sand Bed might be the way to go, or a layer of coarse sand of a mixture of medium sand and mud. Or six inches of gravel!

Well,I gotta go think now...

 

[Gammarus]

I already thought about gravel, just yesterday I believe after reading some of this. Although I figured 5inches would be ok


The sand bed in my 20gallon has yet to form dark sand, even gray sand. That I can see anyways.
Its about a 50/50 mix of play sand and gravel ranging from around few mm to half an inch, with old pieces of crushed snail shell. I figured, if its good enough to be in the river bottom, its good enough for my aquarium.

Honestly I started raising triops with the intention of farming them for puffer food. But they really got me going with fresh water inverts.
Ive yet to identify the small flailing worms in my sand.

My uncle has a small swimming pond, FILLED with bluegill. The substrate is a fine sand, probably ground off stone at a quarry around here somewhere. The depth starts at about 6 inches with clay under it, and then tapers off as the pond gets deeper, down to its max depth of about 4.5ft, where the sand disappears and the pond bottom is ALL clay. Just swimming doesn't make the water murky, however when you get a large party going and every ones disturbing the bottom, and i mean really digging into that clay with your feet, the water eventually blackens, but I believe it is all mulm. It doesn't cause fish die offs when the water is clouded so for a day, and even when you get out, and are covered with tiny black particles, it just smells like pond, and not, what was it, hydrogen sulfide?

It seems that, on this larger scale, a sand/clay layer is EXCELLENT at detoxifying the pond.

Parts of the creek nearby, have a very thin layer of sand, about an inch, with clay/mud under it. Those areas in particular, seem to mostly just produce dark brown silt/mulm clouds when stepped in. There are a FEW areas where it is only mud/clay bottom, and those areas have much more black in them. I should also mention that half the time those all mud/clay spots smell of sulfur. Though only faintly.
Could the initial pass through the sand really help tht much in the other areas of the creek???

Also, I feel like I should remind you, my puffers aquarium has about half an inch of dirt, with half an inch of sand over it, and half an inch of gravel over that, with no filter. Just plants and a very small pump to circulate water. Rarely water change, just top offs usually.

This is a bank.
Every one keeps adding their two cents, and the wealth is piling up fast.

 

[DeeDeeK]

You know, some people act like I'm nuts when I say I don't vacuum. Or do many water changes (except for when there's a nutrient spike and I'm getting ammonia and or nitrite and I have shrimp in the tank).

We're an oppressed minority! Why won't the gravel people let us live with dignity?(just kidding!)

 

[Anoxia]

Right on, Gammarus, taking an idea and running with it. Your uncle's bluegill swimming pool sounds awesome. Bluegill aren't as pretty as koi, but I'm sure they taste better!

That makes me fantasize: if I had an empty in-ground swimming pool to play with, I'd probably do the same kind of substrate as your uncle did (maybe with blackworms!), and turn it into a giant aquaponics set up with tilapia.

I mean, all it takes to turn a chlorine pool into a natural swimming pond is to grow bog plants in about a third of the surface area for filtration, why not grow edible vegetables instead of bog plants? That would be so cheap, and self-sufficient, and environmental, and hippie, I love that idea.

Now all I need is an empty swimming pool, and my dream could come true, LOL. Until then I'll water my tomato plants with old aquarium water, and pretend it's aquaponics... sigh. Excuse me for going waaaay off topic there, I couldn't resist.