Starting a filter-less reef system w/no lights

[Lowell Lemon]

It has been a few months! How did the tanks weather the winter sunlight?

 

[Subsea]

People have already brought up the issue of nutrients, and understandably.

One of the things I’m adding to the ecology part of the curriculum this year is bottom-up and top-down nutrient control. My thinking is that the bottom-up will be handled by two different processes…uptake from a) plants and algae, but also all other organisms like sponges, worms, coral, and the dinos in the coral, and b) anaerobic microbial breakdown as water flows through the deep sand. If I can get the advection down through the bed down to a low enough rate, the water should be anoxic before it goes all the way through.

Top-down will be handled by the usual suspects.

Also curious about whether or not we can get some calcium breakdown deeper in the bed as the CO2 increase and pH decreases.

We have a bunch of different probes that the students can measure that stuff with.

Greg,
I ran a Jaubert plenum with dsb for 20 years. I am convinced that aroggonite at depth in reduced oxygen environment will passively dissolve calcium & trace minerals into the water. @Lasse has run pH probes in his systems and he has background in municipal wastewater treatment as I do.

Initially, the reasoning for Jaubert plenum was to remove nitrate via denitrification bacteria (anarobic digester). With a mature reef, I add ammonia to keep up with nitrogen demand of the system.

Instead of anoxic environment, consider reducing oxygen and Faculative bacteria that require oxygen in a reduced environment. They use much energy to break apart the nitrate molecule and consume the oxygen therby releasing free nitrogen gas molecule.

 

[Gregg @ ADP]

Greg,
I ran a Jaubert plenum with dsb for 20 years. I am convinced that aroggonite at depth in reduced oxygen environment will passively dissolve calcium & trace minerals into the water. @Lasse has run pH probes in his systems and he has background in municipal wastewater treatment as I do.

Initially, the reasoning for Jaubert plenum was to remove nitrate via denitrification bacteria (anarobic digester). With a mature reef, I add ammonia to keep up with nitrogen demand of the system.

Instead of anoxic environment, consider reducing oxygen and Faculative bacteria that require oxygen in a reduced environment. They use much energy to break apart the nitrate molecule and consume the oxygen therby releasing free nitrogen gas molecule.

I was pretty convinced that given a slow enough flow of water through a DSB that I would be be able to achieve an anoxic environment at the bottom of the bed. I was pretty wrong.

I set up O2 probes at various depth in the bed, and found that even at the bottom (20cm+), I was still getting 1-2mg/L O2. This was using Pasco sensors, and I’m not sure how accurate those are. But I can’t imagine they’re that inaccurate. I hadn’t considered that not only might even a low flow through the bed be too high a rate for bacteria to consume all the oxygen, but I vastly underestimated the number of burrowing animals in the bed that had channelized the bed enough to allow for oxygenated watered to flow to the bottom of the bed.

In addition to worms, etc, I also have 2 pistol shrimp that have tunnels that extend 14” or so, especially through the mangrove roots. Some go all the way to the bottom.

So I will take the approach you’re speaking of. I may inadvertently already done so. It’s been a while since I’ve tested NO3, but the last time I tested, I believe it was <10mg/L. I will definitely look more closely into what you’re speaking of.

 

[Subsea]

Greg,
Kudos to teaching Aquatic Science to our future leaders.
You are a “distinguished gentleman” and a “noble scholar”!
A Cajun Aggie in Austin

 

[Randy Holmes-Farley Verified Community Expert]

I was pretty convinced that given a slow enough flow of water through a DSB that I would be be able to achieve an anoxic environment at the bottom of the bed. I was pretty wrong.

I set up O2 probes at various depth in the bed, and found that even at the bottom (20cm+), I was still getting 1-2mg/L O2. This was using Pasco sensors, and I’m not sure how accurate those are. But I can’t imagine they’re that inaccurate. I hadn’t considered that not only might even a low flow through the bed be too high a rate for bacteria to consume all the oxygen, but I vastly underestimated the number of burrowing animals in the bed that had channelized the bed enough to allow for oxygenated watered to flow to the bottom of the bed.

In addition to worms, etc, I also have 2 pistol shrimp that have tunnels that extend 14” or so, especially through the mangrove roots. Some go all the way to the bottom.

So I will take the approach you’re speaking of. I may inadvertently already done so. It’s been a while since I’ve tested NO3, but the last time I tested, I believe it was <10mg/L. I will definitely look more closely into what you’re speaking of.

Maybe the amount of dissolved organic matter is pretty low. Adding an organic might allow O2 to deplete more in the substrate.

 

[Subsea]

Maybe the amount of dissolved organic matter is pretty low. Adding an organic might allow O2 to deplete more in the substrate.

When I add concentrate liquid kelp, would that increase DOC?

 

[Gregg @ ADP]

Greg,
Kudos to teaching Aquatic Science to our future leaders.
You are a “distinguished gentleman” and a “noble scholar”!
A Cajun Aggie in Austin

Thanks. It’s easy to get the students engaged…they have hundreds of gallons of coral reef and freshwater river environments right in the classroom.

I love it because it drives true inquiry. Students ask questions, but I rarely answer them. Instead, I challenge them to devise ways to answer their questions. They have pretty free range to do whatever. You should see my classroom…it always looks like a tornado went through. That’s the product of exploratory and experiential science with high schoolers, I guess :face-with-tears-of-joy:

 

[Gregg @ ADP]

Maybe the amount of dissolved organic matter is pretty low. Adding an organic might allow O2 to deplete more in the substrate.

The first chamber on my sump has at least 2-3cm of detritus. Do you think your idea could be accomplished by pulling that detritus out and embedding/injecting it into the sand bed?

 

[Subsea]

The first chamber on my sump has at least 2-3cm of detritus. Do you think your idea could be accomplished by pulling that detritus out and embedding/injecting it into the sand bed?

Do not disturb your mud filter. It should be crawling with worms & such. That’s the beginning of the microbial food web. Ask @PaulB about MULM.

 

[Randy Holmes-Farley Verified Community Expert]

When I add concentrate liquid kelp, would that increase DOC?

I can’t be sure, but I expect so.

 

[Subsea]

The first chamber on my sump has at least 2-3cm of detritus. Do you think your idea could be accomplished by pulling that detritus out and embedding/injecting it into the sand bed?

Please describe your sump in detail. Earlier, when you spoke about all the micro fauna/fana and detrivores in sandbed was that in the display tank?

 

[Subsea]

I can’t be sure, but I expect so.

It mystifies me. In 55G seaweed growout tanks, I dose 15ml of ammonia twice a day during photosynthesis, as well as a few drops of kelp concentrate. At the end of the day, I get LFS to do my test: Nitrates & Phosphates both showed zero.

 

[Gregg @ ADP]

Please describe your sump in detail. Earlier, when you spoke about all the micro fauna/fana and detrivores in sandbed was that in the display tank?

The sump is pretty simple. Drain chamber goes into what was originally going to be a refugium chamber. But because I have a separate connected macro-algae tank, I just have a couple of pieces of rock in that chamber. It connects to a second equally sized tank w/a 1.5” bulkhead. That 2nd chamber was originally for skimmers, reactors, etc….but because I am not using any of those things on this system, they’re just empty boxes with water flowing through them.

My plan has always been to have more intention with this sump, such as setting up different materials to promote the growth of diverse ‘cryptic’ fauna. For example, I started making baffles from egg crate wrapped in fiberglass screen. I’ve always noted how amphipods really like those mesh media bags that have coarse mesh on the outside and fine mesh on the inside. They really build big populations when they can move in and out through that mesh.

If the structure was more solid (egg crate wrapped in screen), my thinking is that worms, sponges, mollusks etc would populate the exterior, but pods, other worms, etc could freely move in and out through the screen.

I haven looked at the detritus under the scope, but I’ll do that on Monday and post pics here.

 

[Subsea]

“but I vastly underestimated the number of burrowing animals in the bed that had channelized the bed enough to allow for oxygenated watered to flow to the bottom of the bed.“

Dr Ron Shmick was a proponent of dsb filtration using diverse micro fauna & fauna.

Bob Goemans was the curator of Florida Keys reef exhibits after a hurricane with no power at exhibit for 10 days. When he saw crystal clear water in his tanks with under gravel filters, he coined the term NNR (Natural Nitrate Reduction). I suspect he found anoxic.

 

[Subsea]

The sump is pretty simple. Drain chamber goes into what was originally going to be a refugium chamber. But because I have a separate connected macro-algae tank, I just have a couple of pieces of rock in that chamber. It connects to a second equally sized tank w/a 1.5” bulkhead. That 2nd chamber was originally for skimmers, reactors, etc….but because I am not using any of those things on this system, they’re just empty boxes with water flowing through them.

My plan has always been to have more intention with this sump, such as setting up different materials to promote the growth of diverse ‘cryptic’ fauna. For example, I started making baffles from egg crate wrapped in fiberglass screen. I’ve always noted how amphipods really like those mesh media bags that have coarse mesh on the outside and fine mesh on the inside. They really build big populations when they can move in and out through that mesh.

If the structure was more solid (egg crate wrapped in screen), my thinking is that worms, sponges, mollusks etc would populate the exterior, but pods, other worms, etc could freely move in and out through the screen.

I haven looked at the detritus under the scope, but I’ll do that on Monday and post pics here.

You are spot on by establishing separate zooplankton refugiums as you move up the food chain.

PS: Consider pods in the course media bag as a traveling refugium to inoculate new systems are to feed finicky feeders in display tanks. I considered a business model to lease them through LFS and to rejuvenate monthly by bringing spent pod hotel back to refugium and rejuvenate

 

[Gregg @ ADP]

You are spot on by establishing separate zooplankton refugiums as you move up the food chain.

PS: Consider pods in the course media bag as a traveling refugium to inoculate new systems are to feed finicky feeders in display tanks. I considered a business model to lease them through LFS and to rejuvenate monthly by bringing spent pod hotel back to refugium and rejuvenate

To show how oblivious I can be, I just realized this is a thread I started.

That system was torn down when I moved into a new classroom and didn’t have the available space by the windows. It was replaced by my current classroom reef project:
https://www.reef2reef.com/threads/t...th-everything-i-did’-180g-mixed-reef.1027719/