Science classroom natural reef & lagoon- no ‘filter’ or artificial lights

[Gregg @ ADP]

I’ve been meaning to set up a reef and lagoon system in my science classroom for a while, and have finally gotten around to it.

Reefers who really love Neptune controllers, LEDs, skimmers, GFO, chaeto chambers, RO/DI, testing parameters, etc might not get too stoked with this thread, but I really want to see what kind of reef I can create with just water movement and sunlight.

Let’s have fun with this thread. Being a science teacher, I love predictions, hypotheses, data, and analysis. Please feel free to be a scientist or science student and make predictions and offer your analysis here. If you have a good question and a prediction, I will have my students carry out the investigation and measure our results.

Here is the system breakdown:
- heavy duty (1000lb/shelf) storage rack with wire shelves (so light can go through)
-2 20g high tanks, drilled in the top back w/1” bulkheads
- 36” sump (who knows what I’m going to do with it)
- sunlight
- Chicago tap water

I set up one of the tanks last year as a shallow lagoon/mangrove tank. It is set up with a plenum-like system, where I put fiberglass screen on top of some 1” PVC, crushed coral on top of it, and then a few inches of live sand/oolite. There is a riser pipe that comes up from under the plenum, and I’ve had a powerhead in that. The idea is to draw water down through the sand bed and over the mangrove roots for uptake, as well as creating an anoxic zone for NO3 reduction. It took a while for the mangroves to take off, but they finally did.

Now I have set it up so the lagoon tank is above the reef. Because I’m not yet sure of how I want the final set-up to be, I have simply connected the mangrove drain into the reef, and a small powerhead in the reef pumping up to the lagoon. Looks like this before water going in:

 

[Gregg @ ADP]

(I started this thread in another forum but want to move it over here)

I keep thinking I want to put them side-by-side, but I also don’t want to drill another hole in one of the tanks. The more I think about it, the more that seems like the way I might go.

Anyway, I teach biology and enviro-sci, and we do ecology units in each. One of the staple concepts we explore is bottom-up and top-down nutrient control, and this system is meant to show both of those, hopefully in ways students can meaningfully measure/collect data on.

Here’s how it looks currently:

My biggest concern is transitioning essentially AC corals to natural sunlight. So far, so good. I’ve got a couple of acros, a monti cap, bubble-tip anemone, blue mushroom, and leptastrea. They are my trial run, and everything looks pretty good so far. Polyp extension, no bleaching or tissue necrosis. So, going to add some more today.

 

[Sink_or_Swim]

As someone whose favorite class in high school was marine biology, I think this is awesome!

 

[Gregg @ ADP]

The biggest issue I’ve encountered so far is that the powerhead is too powerful and the advection is packing the sand bed down too much.

I don’t need hundreds of gph to go through the bed…50gph is probably more than enough. So I will change that pretty soon.

I will also be adding a small wave pump to the reef tank. What’s a reef without waves?

 

[Gregg @ ADP]

(post dump cont)

This is going to be as natural of a system as I can create.

- no meds
- no QT
- unrinsed/uncured maricultured live rock (hasn’t arrived yet),
- no chem media (carbon, GFO, ion exchange, etc)
- top-off water will be straight from my river system tank that has fish, turtles, tadpoles, crayfish, etc (kinda like a small river flowing into a lagoon)
- obviously no other filtration (skimmer, UV, mechanical, etc)

If I play my cards right, I will have to add supplements. So far, nutrient control seems to be handled pretty easily by mangroves and anaerobic bacteria. The most recent pic shows 2 weeks worth of algae growth…that is with me adding 3 cubes of mysis/other frozen each day.

Also adding turtle grass and manatee grass to the lagoon this week.

 

[Soren]

(post dump cont)

This is going to be as natural of a system as I can create.

- no meds
- no QT
- unrinsed/uncured maricultured live rock (hasn’t arrived yet),
- no chem media (carbon, GFO, ion exchange, etc)
- top-off water will be straight from my river system tank that has fish, turtles, tadpoles, crayfish, etc (kinda like a small river flowing into a lagoon)
- obviously no other filtration (skimmer, UV, mechanical, etc)

If I play my cards right, I will have to add supplements. So far, nutrient control seems to be handled pretty easily by mangroves and anaerobic bacteria. The most recent pic shows 2 weeks worth of algae growth…that is with me adding 3 cubes of mysis/other frozen each day.

Also adding turtle grass and manatee grass to the lagoon this week.

I'm glad you started this build thread here. I'll be watching this experiment as it progresses!
I really like lagoon systems. Yours looks to be off to a great start.

 

[Gregg @ ADP]

I'm glad you started this build thread here. I'll be watching this experiment as it progresses!
I really like lagoon systems. Yours looks to be off to a great start.

Thanks.

I started those mangroves off as propagules almost a year ago. They didn’t do much for a while, and then they sort of blew up. I’m curious to see what their growth does once I’ve added a lot more biomass/nutrients.

Also of note…the sand i used for both tanks was old sand from an existing tank. I literally just siphoned it out of one tank (detritus and all), dumped it into the new tank, and filled with water. No wipe-out @brandon429

 

[Gregg @ ADP]

Going to tag @Lasse because I’m adding some green star polyps today

 

[Gregg @ ADP]

Added some more stuff to both tanks today:

Used my meticulous and pain-staking process for acclimating new animals, aka dump them right in the tank.

1) coral- couple different montis, pocillapora, Grinch porites, and some green star polyps (int he lagoon)

2) fish- 2 purple firefish in the reef, 2 regular firefish in the lagoon (we shall see)

3) other- nice bunch of Halimeda in the lagoon

4) later this week- turtle grass and manatee grass for the lagoon

System modifications:
I was contemplating putting the reef and lagoon side-by-side, but in looking at it today, that would be problematic. There is solid wall between two windows that would block out the direct sun for a couple of hours per day. As I am in the midwest US, I can’t take sun for granted in the winter. The tanks get a total of 6-7 hours of some sun coming in, but 3 of that is angled am and pm sun, so not super intense. So I will just leave the configuration as is.

Next week I will hook the sump up and get that powerhead out of the reef.

Couple of pics from today:

Cleaner shrimp working on prawn goby, while pistol shrimp does a minor rebuild

Zoom in to see new frags. Sun comes in from above and behind, but there is a lot of reflected light off the front panel.

Map turtle soaking up some sun in the river tank

 

[dennis romano]

I set up a tank many years ago in my homeroom. What are your plans for days off, Thanksgiving and Christmas? One piece of advice from my experience is to switch out the sps for softies. The main reason is that the kids will be more interested in the faster growth of the softies. "Wow! That one grew an inch over the weekend!" Softies also tend to put up with more abuse. Best of luck.

 

[Gregg @ ADP]

I set up a tank many years ago in my homeroom. What are your plans for days off, Thanksgiving and Christmas? One piece of advice from my experience is to switch out the sps for softies. The main reason is that the kids will be more interested in the faster growth of the softies. "Wow! That one grew an inch over the weekend!" Softies also tend to put up with more abuse. Best of luck.

Thanks for the reply.

One of the reasons I’m getting the sump hooked up ASAP is so that I can have an auto top-off. Nothing fancy…just a 5 gal bucket where water is gravity-fed to a shut-off valve. There is a decent rate of evaporation, so that is definitely a consideration for longer times away.

I have an Eheim auto-feeder for weekends/breaks as well. There is also some algae growth here and there and it looks like about a million various pods.

Between the 2 tanks, I’m going to have as many different types of coral as I can reasonably fit in them. SPS, LPS, various soft, tri clams, sponges, etc etc. The ecosystem should be sound, so hopefully there isn’t much stress/abuse for the animals.

 

[Gregg @ ADP]

Quick update with some observations:

I think I’ve settled on a final direction for the system. I initially wanted to put the reef next to the lagoon, but the way the windows are, there would be less sunlight going into whichever tank I put on the right. Not to mention, I don’t really feel like drilling another hole.

I’m going to get the sump up and running soon, and I’ve decided to make a true ‘bio-filter’…various zones where filter feeding organisms like sponges, worms, mollusks, etc can be kept and propagated. At least one of those zones needs to be fairly dark, so that’s no problem. I don’t want to use any artificial light, but I do want have part of it lit up…so I’m going to have some of the physics students in the class next door create a sunlight funnel.

This week I added turtle and manatee grass to the lagoon:

The coral seems to be responding to the sunlight. More and more polyp extension. Waiting to see if colors start to change. There’s a lot of particulate in the water…more on that next:



Had to do a little search & rescue this week. I have an orange prawn goby and tiger pistol shrimp together, and the shrimp has been going crazy building tunnels all over the place on one end of the tank. Came in on Weds, and didn’t see the goby. Didn’t think much of it until about 10am, when I still didn’t see it. Finally at about 11:30 I had time to start looking for it. Nowhere in the tank, nowhere on the floor. Then I noticed the tunnel opening had caved in.

A couple of days before, I took the powerhead out of the riser and put an air stone in, because the level of advection was too much and the sand/substrate was getting compacted. Well, that was also part of what allowed the shrimp to build its tunnel maze. Once the powerhead was out, the substrate bed loosened up and a lot of the tunnel collapsed…with the goby in it. Dug around for awhile and finally found it…it was fine, and reconstruction by the shrimp has already commenced.

Now what I need to do is find a pump that will pull enough water down through the bed to deliver nutrients to the roots and give the bed some level of firmness, but not so much that the the bed gets compacted and that there is still O2 by the time the water gets through the substrate. I want there to be anaerobic reduction, and if there is too much water going through the substrate, I think there will still be O2 available at the bottom.

 

[Gregg @ ADP]

The next step (hopefully this week) is to add maricultured live rock from a place like KP or Gulf. Especially once the sump is set up, I want all the goodies, including some natural sea water.

 

[Gregg @ ADP]

Some interesting happenings and observations:

1) Lighting, first and foremost- my biggest concern going into this thing was how the corals would react going from LED to direct or even indirect sunlight. It seems like anytime we move corals from one artificial lighting scheme to another, there is some sort of adverse reaction (closing up, bleaching, necrosis, etc).

So far, after between 1 and 2 weeks, the opposite has occurred. Not only has there not been any sort of adverse reaction, there has been good-to-full polyp extension and visible growth in all corals added to the tank. I was not expecting that.

I have some ideas, but what are all of your thoughts/hypotheses on why this is happening?

2) Increasing bio-diversity- seeing some bryopsis growth and about a zillion pods. No bryopsis growth in lagoon, but there are some herbivores in that tank. I’m good with letting it go a little before adding herbivores to the reef tank. The pods were not a surprise, but the numbers were.

3) today added a few more acro frags (from 1 colony) to the reef tank, and a few branches from an old-fashioned branching frogspawn to the lagoon. In regards to their 1st ever encounter with the sun…they opened up immediately.

Pics shortly.

 

[Gregg @ ADP]

Hypothesis challenge #1:

Captive routinely exhibit a stress response to change in lighting, whether it’s type or intensity. Withdrawn polyps, bleaching, and sometimes even necrosis and death follow changes in artificial lighting, so we typically ease corals into new light environments.

Yet the corals in the classroom tanks went from LED to full and direct sunlight, with no sign of stress response from any of the ~20 different corals (representing ~8 different species).

Why did the corals not fry in the sunlight?

 

[Gregg @ ADP]

Minor update:

Oh, my poor corals. 7 straight cloudy/rainy/snowy days here in Chicago

They actually seem just fine, but I had gotten used to seeing bright, intense sunlight filling the tank, and the reef under cloud cover is a little underwhelming. I have a nice ATI LED/T5 combo light just sitting there staring at me, and it’s taking everything in my power to resist putting it over the reef.

Anyway…here is a happy frogspawn:


One thing that did happen (before the cloudy weather spell) is that one of my mangroves sprouted new leaves, but they were yellow. I know with plants, that’s typically a sign of lack of water. The others look fine, but there isn’t much new growth with the short days and cloudy skies.

We are stuck in the school next Friday after the semester ends and grades are put in, so there won’t be much for me to do. I think I’m going to slightly tear this system down and move things around, set up the sump, etc. I wish I had a lot more room. The big issue I have right now is that the sunlight is coming in from opposite direction that the tanks are viewed. I’m curious how the colors look when the angle of incidence is more in my favor.