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Classroom Ecosystem

16K views 107 replies 15 participants last post by  rakali 
#1 · (Edited)
I set up a planted tank for my daughter's kindergarten class. I've had planted tanks for years. I like the Walstad approach with an Amano aesthetic. For this tank I was hoping for a setup that would survive during the summer with little to no intervention. I was inspired by Tom's Bucket o' Mud and his ability to leave the tank alone for 6 weeks at a time.

The tank I have to work with is a 20gal high tank. I put in a small power head (restricted) for circulation currently located at the top of the tank. I split the tank up with a plastic mesh to create a refugium against the back of the tank. So far I added gammarus (with green water), snails, and a mix of hitchhikers that came along with the gammarus. I seeded the whole tank with a good amount of filter sludge to aid in cycling. I'm adding moina in about a week and cherry shrimp not long after that. I'm also considering adding some blackworms. I'm interested in adding anything that will reproduce, without additional food, that could be eaten by small adult fish.

The tank is heavily planted with a variety of random plants (Az Gardens mixed potted plant special) and there's two anthuriums planted in shower caddies riparium style in the back and a good amount of driftwood. I'm covering most of the plastic mesh with java moss in a few days. I added some oak leaves to the refugium along with some hornwort that came with the scuds. I also plan to add some of the java moss back there as I know cherry shrimp love to breed in it. Substrate is a mix of Fluval Plant and Shrimp and black flourite. The light is Fluval Plant Spectrum 3.0.

For fish I was thinking a couple of otocinclus and around 10 white clouds to be added in about a month. Hoping that a low fish load will make this whole idea possible.

I could use some help with suggestions for making the refugium work (best organisms, approach, etc.) as well as it can. Anyone who's had experience with freshwater refugiums please share your wisdom.

Also all opinions/advice welcome! My goal is to make this a pretty self contained little ecosystem. I'm going to add a partial cover to the tank to minimize evaporation. I'm hoping this will be a no feed tank that only needs an occasional top up due to evaporation.

I'll post some pictures shortly and document the tank's progress here as it goes along.
 
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#2 · (Edited by Moderator)






After seeing Michael Langerman's video I biked up to Central Park and collected a bunch of plants, a few leaves, and some snails. I'm hoping to make mini plastic cup tanks like Michael has for each of the kid's to take home. Additionally I'll culture some myself to add more diversity to the tank.
 
#3 ·
Very cool start. Looks like its going to be a interesting tank setup and I am sure the kids will love it.

Not so sure how well leaving it over the summer will work with the fish but no expert myself on setups like this. You would be surprised at how quickly 10 of any predatory nano fish will clean out a tank of its small organisms. My 10G which has my betta and some amano shrimp had a huge amount of little critters and detrious worms cruising all over the tank. I added 5 chili rasboras and it was cleaned out in under a week. Well atleast all the stuff you could see anyway.

Hopefully you can attain more of a balance with yours in that respect.
 
#4 ·
Thanks for your reply! Yeah I'm hoping to stock the hell out of the refugium with adult organisms that are too big to pass through the screen (shrimp, daphnia magna, etc.) The tank will find it's balance. It could end up that there's no fish left come start of school. Hoping it won't come to that.

Also hoping that rounding out the ecosystem as much as possible will lead to better health all the way up the food chain. We'll see.
 
#7 · (Edited)
A few updates on the tank. In a different thread I asked for recommendations for fish for the tank and @tamsin recommended Endlers because they are bold and beautiful as opposed to CPDs which are also beautiful but shy. They also recommended only males which makes a lot of sense. So for now Endlers are my front runner. I read here that Endlers do not need a heater and that it may actually increase their longevity to have them in cooler water. I am considering hardening up the water a bit as I read that this is better for the shrimp and preferred by the Endlers.

I've been devouring all the old @auban posts and his tricks post was really illuminating. After reading it I bought Astaxanthin to make greenwater and Catappa Ketapang leaves to make black water.

I also decided to go back to the original Tom's Bucket o' Mud post that inspired this whole approach in the first place. I found his list of critters and basically ordered everything I was missing.

Tom's list:

"I added (at various points), shrimp, Hyalella and several species of daphnia (big ones got gobbled up very fast but I have a tiny species that hangs on the substrate that still appears from nowhere whenever I have a tank without fish in it - a bit like a mini ostracod). Other than that ostracods, cyclops, freshwater limpets and various other microfauna seeded themselves really. Also had less welcome planaria, hydra and leeches at various points.

I've also now got Asellus and Lumbriculus in some tanks which both make excellent additions. My new Paros are going mad for the Lumbriculus - the worms bury in the substrate with one end waving in the air, which the Paros bite off with glee. Apparently just about any Lumbriculus segment is able to regenerate into an entire worm so they should just grow back."

I already had the scuds and shrimp are coming soon. I ordered moina and daphnia magna which should arrive shortly. I found the Lumbriculus at Carolina Biological supply and they seem like the perfect worm. Thinking I need to add to the mulm before the worms arrive. There's currently a thin layer of filter sludge which will be a good start but I'll need more. I've been collecting oak leaves. Maybe I can make some kind of slurry in the blender with them. I also want to add nori which my cherries have loved in the past and it really makes their color pop.

Found this nice mix of crustaceans (Daphnia, Alonella, copepods, ostracods, aquatic isopods, amphipods) from Carolina which should just about complete Tom's list. Well everything but the limpets and the Asellus. Although Tom did so much wild collecting who knows what else was in there.

My java moss order finally arrived and like a dumb ass I only ordered one portion when the seller who was running a 2 for 1 sale had agreed to send me 5 for the price of 2. Doh! I ordered a few other orders from another seller. Hopefully it's enough. I want enough to cover most of the refugium mesh and some to add to the refugium.

Also I'm having thoughts about my pond collection. I'm not seeing any ostracods which are what I was really hoping for and I'd rather not get any weird worms that won't be helpful. I think I may just return the samples to where I got them from. Thoughts?
 
#8 ·
This morning I checked on the tank and the greenwater is getting thicker. On the one hand I'm glad. I added greenwater to help support the scuds and daphnia (I'll be adding shortly) and other infusoria but on the other hand aesthetically the greenwater makes the tank look bad. The teachers in the class understand that this is an ecosystem tank and that the water won't be crystal clear but there's still part of me that wants to throw a filter in there and make the water clear. Hopefully the addition of the daphnia will help increase clarity a bit. Sometimes in the pursuit of aesthetics we compromise the health of our tanks I think.
 
#9 ·
Great thread - and good on you for doing this in a classroom! I bet those kids love it! My son's pre-k class has a 10 gallon tank with 2 goldfish (that are each about 1/3 the size of the tank). Makes me so, so sad.

Sometimes in the pursuit of aesthetics we compromise the health of our tanks I think.
Absolutely. Clear water is beautiful, but when you look at bodies of water in nature, often they are green, or brown. And life thrives. Too bad a lot of newbies to the hobby are coached/chastised that these things are "bad" when in fact, they are signs of health for an ecosystem.
 
#10 · (Edited)
Did a little presentation on the tank for the kids today. They seemed to enjoy it.

Bought a cover to help with evaporation and bought a mount for the heater the tank came with that was missing. LFS said set it to 78.

Adding two peace lillies tomorrow. Bought some dollar store jars for setting up some daphnia and other cultures in case the tank crashes.

Bought some crushed coral that I'm going to put in the refugium to up the PH and the GH. LFS said shrimp will need it.

I'm going away for a week starting Saturday. Hopefully nothing freaks out. Lots of organisms arriving this week (daphnia, moina, blackworms, asellus, ostracods, isopods).

Here's the slide I made to show our little ecosystem.

 
#11 · (Edited)
Today I fitted the cover and it was too big. I looked up a glass cutting place and realized how few are left. People don't hang pictures or art much anymore. When I finally did find someone he cut the glass for free.

I added two peace lillies as was suggested here and at my LFS. The shower caddies are now full.

I added the crushed coral and I think I got a slight bump in PH to 6.8 but with these test strips it's hard to tell. But at least things are headed in the right direction.

I added the heater which was missing mounts (I bought some yesterday) and set it to 76. LFS said 78 but I figured better to get there gradually.

The big news is the mixed crustaceans arrived from Carolina Biological. I was happy to see daphnia, ostracods, and copepods but so dissapointed to see no asellus that I called them. They said you get whatever is available but did offer to refund. I accepted the explanation and told them it wasn't necessary. If anyone has some aselus they'd be willing to share I'd appreciate it. We've blown through our budget.

I also got black worms. It's funny because I was thinking about black worms because I fed them to puffers in the past and then I saw Tom mention Lumbriculus and I ordered them thinking they were some kind of fancy worm not realizing they were just black worms. I looked up how to culture them and found this informative page. They recommend chopping the worms up to stimulate regeneration and to increase the size of your culture. I had to psyche myself up a bit to do it but the deed is done.

I now have two culture jars set up in the classroom. One with the crustaceans and one with the worms. I'll be setting up a daphnia only one shortly too when the big daphnia order arrives. I'll also have eggs for daphnia magna that I need to hatch and add over the next few weeks.

It was good to see the tank with more emergent plants and all the little critters swimming around. Numbers still look good too.
 
#14 · (Edited)
@Streetwise Here's some pictures and videos from this morning. Next time I'll shoot with a polarizing filter to minimize the reflection.





This is the refugium. It's sits behind a screen in the tank. It currently contains oak leaves, Indian Almond leaves, java moss, hornwort, and some cooked vegetables I added last night.



That's my daughter pointing out a snail. The teacher and I discussed creating laminated cards that list all the organisms for the children to find and identify. We want to turn it into a game.



These are the culture jars. I set them up by mixing filter sludge in with the gravel and water. They both contain hornwort, small pieces of java moss, and cooked vegetables. The jar on the left is the Carolina Biological mixed crustaceans and the jar on the right is black worm. The water is cloudy because it's greenwater from the tank.

 
#17 ·
This tank is only a bit over two weeks old. This is my first riparium. This tank is in front of a window that faces west and gets partial sun. Also because it's a classroom there are bright flourescents overhead. From a plant care website I read the following
Anthurium plants can tolerate all levels of indirect light, but anthuriums growing in low light will have fewer flowers and will grow slower. These plants cannot tolerate direct light however, as this can burn the leaves. It grows best in bright, indirect light.
The guy in my LPS said peace lillies were low light but I didn't double check. If you look up anthuriums grown in water you'll see it's pretty common. Good luck with yours!
 
#21 ·
Away for the week and already missing the tank. Wondering how it's doing? Are levels good? Are organisms thriving or declining? I think I messed up those culture jars. Too much filter bacteria. One of them seemed funky. Hopefully the whole culture doesn't die off. Also the substrate was releasing bubbles. Makes me think things were not going well. In hindsight all they needed was greenwater. Hopefully they pull through.
 
#22 ·
Rakali I am very impressed. In a way you are doing what I am trying to do myself. I have a grow-out tank full of scuds, pods and cods. I intend to make an order for aquatic isopods and a few others. I like how you are allowing your plants in the fuge section to grow emerged. I am going to do that also with cattails, Temple Compactus, and a few native plants. I am going for a build that would remind one in a way of a reef tank but without the expense. I too am striving for as much diversity as possible. One of the most impressive aspects of your setup is that it is in a 20 high yet it is so well put together so it seems larger than it might otherwise. I also like the refugium idea. It is awesome that you are inspiring your students, presenting fish keeping and teaching them about all the different creatures one can find in freshwater. Bravo! Almost forgot to tell you that the bubbles you see are likely CO2 from decaying bits of organic material in the soil. I have them too.
 
#23 ·
Thanks so much. I'd love to see your tank and I'll accept your request as soon as I can figure out how to do it on my phone. Also the bubbles I was referring to are in the culture jars not the main tank thankfully. I believe you are correct. Probably the cooked vegetables I added. I think I went a little overboard and put too much in.
 
#24 · (Edited)
How much of the cooked veggies did you put in? If you only added little pieces to each jar all is good. The planktonic animals and algaes will benefit but if you put a lot in the resulting ammonia spike could wipe out everything in those jars including the greenwater. Those jars are 1 quart Mason jars it looks like. I seem to remember the pic of your jars and I don't think you overdid it. Now if there was no substrate I'd be much more worried. I need to get some live blackworms to culture speaking of culture jars.

I just looked at the pic of the jars. You definitely did not over do it with the veggies. You may want to get a strainer lid for each culture jar so they get O2 if you haven't already. Of course you can put some air holes in the normal lids if you don't want to purchase strainer lids.

I can't wait to see this build come together considering the great start so far. I am subscribing to this thread for certain!
 
#25 ·
Thanks for your feedback. I punched holes in the lid but at least one of them seemed pretty funky. On the plus side if there is a little ammonia spike I told the teacher to add some of it to the tank so it will aid in further cycling. I'll know tomorrow how they are doing. I got a small order of black worms from Carolina Biological. Look them up by their scientific name if you don't have another source. I remember when you could get them at LFSs.
 
#27 · (Edited)
Week 3 Update

Back from vacation and tank is looking great. Daphnia population exploded while I was away and cleared most of the greenwater which is great for visibility but not so great for the daphnia population which is probably going to crash if I don't get more quick or add yeast I guess. I got some ASTAXANTHIN powder to make greenwater as @auban suggested but the quantity is pretty small and I'm not 100% sure it's going to work. Might just add it to the tank and see what happens. Might also reach out to the person who sold me my scuds, which came in greenwater, and see if they can sell me just greenwater. If anyone has greenwater they'd like to donate I'd appreciate it. Happy to pay for shipping.

Thinking of setting up an auto top up with a plastic bin filled with greenwater to keep the daphnia going and to combat evaporation which seems to be an issue with this heated tank. I've never set up an auto top up so if anyone could point me in the right direction that would be great. I have no running water in the space but there's power and a space to put a bin below (behind) or above the tank.

Added some filter media to the outside of the power head just to disperse the suction of the inlet a bit so as not to suck in too many organisms. Added some java moss to the refugium although it wasn't looking too good by the time I got it in the tank. I'm going to add a light to the back of the tank for the plants in the refugium. The refugium screen really cuts the light down.

The culture jars crashed as expected. They really stank when I cleaned them. Set up another one with just gravel and tank water for Moina and some Daphnia Magna just as insurance. Probably need to add yeast or spirulina to that pretty soon. Hoping the other organisms like the blackworms will reproduce enough in the refugium that another back up culture will be unnecessary. Right now everything seems happy. Worms are all over the substrate. I see copepods zipping by, scuds are happy, seed shrimp are multiplying. So far everything I've put in the tank seems ok with the exception of a few of the plants.

Cherries arrive this week and I think the tank is ready for them. The numbers have been rock solid for 3 weeks and the crushed coral I added brought the PH up to 6.8 which is right where I want it. I've added fish food to the tank a few times in the hopes that it will help ensure cycling has occurred. The snails certainly make a lot of waste so from a bio load perspective I'm hoping the RCS will be fine.

Here's the latest pictures and some videos that really show the daphnia. it kind of amazes me that this tank is only 3 weeks old.





 
#28 · (Edited)
RCS arrived today and I added them to the tank. They came in two little bags so one went in the refugium and one went in the main tank. I'm going to add nori tomorrow. It's my cherry secret weapon. They love it and it seems to make their color really pop. Also in my experience it doesn't foul the tank.

I'm a little worried about the daphnia population crashing. The greenwater was completely gone this morning. The water was crystal clear. I added some spirulina and barley grass powder. I mixed a small amount in a jar with some tank water and then added it to the tank. Does anyone have a recommendation for daphnia feeding amounts? I read somewhere that you really don't want to overfeed them. I'm worried the greenwater may have done just that. Thoughts?

I'll add some pictures of the RCS in the tank/refugium tomorrow. I had this panicked thought that the babies would be too big to pass through the refugium mesh but I can see that won't be a problem.

With the daphnia multiplying like crazy I'm considering introducing the Endlers sooner than later to cull the population a little. Another alternative would be to set up little pasta sauce jar mini tanks with daphnia for each kid. I'd need to make about 20 of them. I could send them home with some barley grass/spirulina mix and some small spoon for feeding. Need to find the magic amount that would keep them alive but not reproducing so much to fill the jar. Thoughts?
 
#29 ·
RCS seem to be doing well. Attempted version 1 of an auto top off. Failed because I am trying to use gravity feed and the container I was using is not solid so it just crushes as the water pours out of it. Version 2 will use a more rigid water cooler bottle.

Just received my little clip on polarizer but not before I took the photo of the refugium with the big light reflection.


 
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