DSB (Deep Sand Bed) for Freshwater

[Fishn']

I have been looking to build to the next step, as I usually always am. I've been doing some research (reading, YouTube, the Internets) about DSB for a fresh water tank. I do understand the risk/concern of gas bubbles forming and being released... causing a mass fish kill.

Has anyone ever done this "properly" or have done their research and are considering?

Here is what I know so far:

1) 5-7''s depth of consisten grain size sand. Pool filter sand or horse racetrack sand is rec.
2) Do not disturb once it is set up.
3) Always follow rule #2.
4) Do not keep fish that like to dig.
5) Snails that burrow and worms help to transport nutrients deeper into the sand.
6) Heavily planted is preferred.
7) The first 6 months are a little messy as you let the detritus and waste build up before it starts to break down.
8) The sand will turn black at the depth where anaerobic activity occurs (side view through glass).

It is simply a curiosity to see if it could be done. I know some refuse tanks use "bog mud" for this purpose.

Thoughts? Experience? Opinions?

 

[CSnyder00]

I just wouldn't take the risk of an air bubble of epic proportions building up. I have a deeper sand bed in my 40 gallon that is about 2" deep and it builds up some pretty big sized bubbles from time to time under the décor. If you were to get a large enough build up, it could be bad. That risk alone would deter me. If it were more porous substrate that was heavier and there was less of a chance for bubbles to form/burst, I'd take a shot. Otherwise, nope. I'd steer clear. Just my opinion though. You could mimic the look by putting a layer of black sand at the bottom and then some lighter sand on top if the look is what you want.

 

[dogofwar]

I think that Sonny Disposition (Bob) tried this.

Maybe he's got some tips...

Matt

 

[FishEggs]

What would be the reasons/benefits of doing a deep sand bed?

 

[Fishn']

What would be the reasons/benefits of doing a deep sand bed?

From what I understand, nitrate breakdown.

Don't get me wrong, water changes will always be required, but I find it very interesting aspect of the hoby to try and inch closer and closer to a naturaly maintaining and functioning habitat as we can extablish. Still a closed biological system, so there may always be limitations.

I look at the evolution of aquariums; live plants for reasons beyond aesthetics, biomedia, filters such as sumps that simulate organic filtering processes found in nature, etc... I feel this is a possible next step. A "working" river/lake bed.

 

[Cal]

Have you seen Cory's video where he visited the "no water change" fish store? My substrate is about 4-6" in my 55gal. The tank is heavily planted. It's been running for approx a year and I haven't had any issues with epic gas bubbles. I do have MTS that help aerates the top layer of my substrate. But who knows, I might be building up an epic gas in my substrate with out me knowing.

That being said, I've never seen my nitrates go above 40ppm after the 6 month mark. This is with adding fertilizer weekly and no water changes. I've gone 6 weeks with out a water change (only top off) and my nitrates were under 20ppm. I don't know if my low nitrate situation is happening because of my deep sand bed or because of the tank being heavily planted.

 

[Fishn']

Have you seen Cory's video where he visited the "no water change" fish store? My substrate is about 4-6" in my 55gal. The tank is heavily planted. It's been running for approx a year and I haven't had any issues with epic gas bubbles. I do have MTS that help aerates the top layer of my substrate. But who knows, I might be building up an epic gas in my substrate with out me knowing.

That being said, I've never seen my nitrates go above 40ppm after the 6 month mark. This is with adding fertilizer weekly and no water changes. I've gone 6 weeks with out a water change (only top off) and my nitrates were under 20ppm. I don't know if my low nitrate situation is happening because of my deep sand bed or because of the tank being heavily planted.

So you have only been topping off the tank and not doing any water changes? Or do you just haveess frequent water changes?

 

[Cal]

Currently I'm doing 50% weekly water changes. I've been on this schedule since I got some boesmani rainbows, I didn't want to risk them getting sick.

4 months ago, I was doing a water change every 4-6 weeks but I did add 0.75 gallons to the tank weekly due to evaporation. I wanted to test how long the tank could go before I would see elevated nitrate levels. I never saw an elevation in nitrate levels but ended up doing a water change in fear of "it's been too long."

 

[Fishn']

Currently I'm doing 50% weekly water changes. I've been on this schedule since I got some boesmani rainbows, I didn't want to risk them getting sick.

4 months ago, I was doing a water change every 4-6 weeks but I did add 0.75 gallons to the tank weekly due to evaporation. I wanted to test how long the tank could go before I would see elevated nitrate levels. I never saw an elevation in nitrate levels but ended up doing a water change in fear of "it's been too long."

What was your goal in trying this? Sand or gravel? I appreciate the feedback!

 

[Cal]

I have pool filter sand on the bottom, I got sick of the color and added eco complete on top of it. The only goal was to keep nitrates low which worked, but not sure if it's from plants or deep substrate. Probably a little bit of both.

 

[Fishn']

I have pool filter sand on the bottom, I got sick of the color and added eco complete on top of it. The only goal was to keep nitrates low which worked, but not sure if it's from plants or deep substrate. Probably a little bit of both.

Thank you for the feedback Cal. I'm considering this set up in the near future.

 

[Cal]

This is one of Cory's recent videos. There's a lot of good points and some interesting questions he brings up with water changes.

 

[Fishn']

That is a great video and on point. I back up with what Cory says that we are keeping ecosystems. To me, that is the most intriguing aspect. I feel that the possibility and challenge of keeping a DSB, if successful, would be another added positve for the ecosystem. Water changes will always be a part of the hobby, but it would be great to make the aquarium that much more sustainable.

I have a 20 long that is minimaly touched. Sand subtrate (2.5" depth) with argentinian sword plants, an amazon sword, valsenia covering 25% on one side, small staurogen foreground cover, and frogbits floating over roughly 30-40% of the surface. Eheim glass cinder substrate in one canister tray and biohome in the other tray. I chamge 25% every three months and top of the water when needed. It is always at 20 nitrates and undetectable nitrites and ammonia. My blue rams are breeding like crazy, my apisto pair has bred twice, and the shrimp keep multiplying. I think it's all going down in the valsenia forrest. Lol.

Best part for me is a highly stable small aquarium with minimal input.

 

[CSnyder00]

I love the idea. I may have to look more into this. Thanks for the info.

 

[chriscoli]

Although I haven't had a chance to watch the video yet, I've been intrigued by the same concepts. Anaerobic processes are by nature, very slow. So the aerobic side of the cycle will often outpace the anaerobic side. Also, some more food for thought - I heard a few years ago that the reason tanks with thicker poret foam (3 inches or greater) do so well is that it allows for more anaerobic activity.

The black layer in the substrate indicates the presence of H2S which will precipitate metals especially iron, showing up as black stain on things. In an iron limited environment, the black might not be as obvious but you could still have H2S. H2S is extremely toxic because it binds irreversibly to metals....including trace metals that are essential for our electron transport chain (i.e ATP processes) in our bodies. Most organisms have ways of dealing with small amounts of it, and organisms that are from environments that are rich in H2S, often have very good ways of dealing with it. If you have gas bubbles in your tank, give them a sniff. seriously. if it smells like rotten eggs, you've got H2S. If it's unscented, then it might be N2 which is the byproduct of the anaerobic side of the nitrogen cycle in your tank (Nitrate goes to N2 under anaerobic conditions) which is what you're trying to achieve with the deep sand bed.

 

[CSnyder00]

Christine says - Let's do science!

 

[Fishn']

Although I haven't had a chance to watch the video yet, I've been intrigued by the same concepts. Anaerobic processes are by nature, very slow. So the aerobic side of the cycle will often outpace the anaerobic side. Also, some more food for thought - I heard a few years ago that the reason tanks with thicker poret foam (3 inches or greater) do so well is that it allows for more anaerobic activity.

The black layer in the substrate indicates the presence of H2S which will precipitate metals especially iron, showing up as black stain on things. In an iron limited environment, the black might not be as obvious but you could still have H2S. H2S is extremely toxic because it binds irreversibly to metals....including trace metals that are essential for our electron transport chain (i.e ATP processes) in our bodies. Most organisms have ways of dealing with small amounts of it, and organisms that are from environments that are rich in H2S, often have very good ways of dealing with it. If you have gas bubbles in your tank, give them a sniff. seriously. if it smells like rotten eggs, you've got H2S. If it's unscented, then it might be N2 which is the byproduct of the anaerobic side of the nitrogen cycle in your tank (Nitrate goes to N2 under anaerobic conditions) which is what you're trying to achieve with the deep sand bed.

Excellent info, thank you for posting.

 

[Sonny Disposition]

I think that Sonny Disposition (Bob) tried this.

Maybe he's got some tips...

Matt

I have three sand tanks, but I wouldn't call them "deep sand." They each have 1 1/2 to 2 inches of sand, and have never accumulated trapped gas. It's helpful to agitate the sand before water changes, to free some of the trapped material. Earth eaters are helpful, too. I think the denitrifying bacteria that colonize the sand really help keep the water clean. In my sand tanks, I only have mechanical filtration-- a cage over power heads, and don't have any problems with water quality.

Given the results I've had, I've never seen the need to use more sand and develop an anaerobic layer.

 

[Fishn']

Floating plants can handle nitrates as well I believe.

 

[chriscoli]

Most plants are actually so-so on nitrates (hornwort will consume respectable amounts of nitrates as well as some terrestrial grasses). Most plants really like ammonia, though, so having plants in the tank usually reduces nitrates by not allowing them to even make it that far in the cycle rather than direct consumption of nitrate. Floating plants can use more nutrients than submerged plants because they don't have to worry about CO2 being limited.