Tiny tank basic reqs for an NZ rockpool aquarium?

[Ellesea]

Hi all - a brand-new nano-tank wannabe here.

 

I am based in Wellington, NZ, and after our country was put into lockdown, I finally followed a wee idea of setting up a "closed ecosystem" from the local rockpools. I collected sand, sea water, cuttings of various seaweeds/kelps/etc, and some small sea snails/limpets on loose rocks/whatever was in the seaweed and sand.

Before we go further: I want to acknowledge that I should have done more research. Closed ecosystems are typically fresh water for a reason, and I didn't know this. I just figured that all those videos on YouTube and the how-to guides found on Google (mostly aimed at showing small children the variety of life in ponds) were freshwater because for most of the world, freshwater is more accessible than seawater, and not all of the coastline is compatible with setting up interesting ecospheres anyway. So, I know, I was a moron.
 

That said: I have really enjoyed watching it and I'm pleased with the results - but I've recently realised that my jar isn't sustainable, because... It's a jar. It's a big jar (2.65L, which I think is 0.7 US gallons), but that doesn't change the fact that it's a poor home for all these beauties. Initially I planned to return them all to the water, but things have stabilised for now, and so I am currently choosing to press on with this experiment of mine, but to improve it as much as I possibly can.
 

So, I want to set up a small tank - VERY small, as in I've found a 13L tank (3.4 gallons?) that can fit on an empty shelf in my apartment. I want to make it as happy a home as I can for some very small rock pool creatures with basic needs, e.g., isopods, snails, small crustaceans, and hopefully anenomes. I am not expecting to be able to keep "complicated" creatures (e.g., fish, soft corals) happy so am not looking to have any. My knowledge of what typically lives in a rockpool tends toward being only marginally above my knowledge of life on Mars, though, so if you scoffed at what I deem to be complicated (vs. "simple"), please scoff very publicly and teach me your ways!

So yes: I'm an absolute beginner. To call me a novice is giving me far more credit than I'm due, and I would love advice and information.
 

If this tank idea seems reasonable, can you please advise what sort of lighting and filtration/water circulation might be good? I like the idea of a rockpool tank as from I can guess, these creatures can probably cope with some changes in salinity, short periods of stagnation, etc, more than others. From what I've read, it seems I'd need to mark the tank to know what the water level should be, and occasionally top it up with purified water, but what else? The tank I've been looking at has LED lights included (red, blue, and white) but I'm not sure if they'll be the right strength.
 

I have seen that bubblers in saltwater tanks can create "salt creep", so I'm thinking a small fan might be better to create a bit of a current and encourage water circulation, BUT I also don't want to stress anything by making it too noisy (but would creatures living in a rockpool that's often pounded by waves even care?!). Help! Other than providing light and adequate water circulation, my goal for my tank is for it to be more-or-less self sustaining, so no me needing to feed things or do much in the way of water purification/pH and mineral balancing, etc. ... Oh. and will I be likely to need to cool the water? Or, as a rockpool tank, will room-temp be OK?

Finally, I'd like some advice on the ratio of things to put in the tank (i.e., sand to water to plants to rocks), and what little beasties would be happy. I have a particular passionate love for anenomes so am really hoping to be able to have some, but as I've implied - I want animal welfare to be my highest priority here.

Here's an Imgur album of the jar, on day 2 or 3. It's now been over a week and is still looking pretty good, though not quite as happy.

Thanks so much!

N.B., I tried posting almost this exact thing on reddit and got zero replies so if someone's seen both of these posts - yep, still me.

Also - just seen how much I wittered on. Here's a TL;DR:

- I wanna set up a self-sustaining NZ rockpool tank
- is 13L a big enough tank for a few very small beasties?
- what lights will be best?

- what water circulation method is best?

- do I need anything else, e.g., something to cool the water?
- what things should go in the tank? (e.g., how much water to sand; plants, animals, rocks)
- I care deeply about animal welfare so if this is a bad idea, say so, please.

 

[billygoat]

Hmm... interesting. This is how the first aquariums were born, with people just collecting things on the shoreline and trying to observe them in a captive environment. I admire your curiosity, as well as your drive to do what is necessary to keep these animals alive, but I think you might be in for some challenges. 

 

A 13 liter tank would probably be fine to keep many of the plants and animals you find in tidepools along the coast. They are used to being confined to tight spaces, and in fact many of them don't move much anyway. However, when it comes to filtration and especially heating, some issues become apparent. Some quick Googling has taught me that the coastline near Wellington is a temperate ocean environment, which is a habitat that is dramatically more difficult to replicate than the tropical tanks that you see (almost) every reefer running. Ocean temps in that part of the world seem to average between 18 and 11 C, depending on season; in order to keep your tank at this temperature you would need to acquire a chiller, which is a very expensive piece of equipment. You may also have issues with condensation on the glass due to the difference in temperature between the water in your tank and the air in your home. For this reason most cold- and temperate-water aquariums are specially constructed out of thick acrylic rather than glass, as it's a better insulator and helps reduce condensation. 

 

Filtration for your tank would also be challenging. Before a saltwater aquarium is ready for livestock, it must be seeded with beneficial bacteria that convert the waste products of your tank's inhabitants into less-toxic compounds. This biological filter is absolutely essential, because without it your animals will poison themselves with their own excretions. This "cycling" process usually takes 2-4 weeks in a typical tropical tank, but when you lower the temperature, everything gets slower... including the speed at which bacteria establish themselves. Cycling a cold-water tank can take a very long time; in fact if it were me I'd probably cycle it for multiple months with no livestock in it, just to make sure that the biological filter gets going. 

 

Lighting would be easy, as pretty much any light (even a freshwater aquarium light) would likely be fine for the creatures you're thinking of keeping. Some sort of water circulation would also be necessary for gas exchange, though I am not sure it would need to be very intense. 

 

All things considered, keeping a temperate tank of any size (at least in the long-term) presents quite a few difficult and expensive challenges. I cannot in good conscience recommend that you try it as your first aquarium. If you'd like to learn more though, I recommend you check out a few of the cold-water Tank of the Month articles here on Nano-Reef. These systems are very similar to what you're thinking about setting up (minus the fish and other more complex creatures, of course).

 

Good luck! I hope this is helpful.

 

[SliceGolfer]

I remember seeing this last year which is similar to your first attempt. I found it interesting.

 

 

[Ellesea]

Hi to both of you!

Thank you very much for the advice (and the video, SliceGolfer). Additionally, I ended up releasing my jar today, as I could see that - as you stated, Billygoat - the aquarium was beginning to poison itself with waste. So, back it went to the water it came from, and hopefully I didn't harm any of the beasties 😬

I'm not totally averse to taking on costs that are higher than I anticipated, - it's the price of animal welfare, IMO, and thus necessary if I want to continue this idea. 

Billygoat - you say I'd need to seed the tank. As an interim/possible alternative, would it be feasible to take rock-pool water, sand, plants, etc, do my best to avoid any creatures large enough to be seen and excluded, and just let that settle for a while? Assuming I get aeration/temp/tank requirements met, that is. Would that water have the beneficial bacteria needed?

I know I'd end up with some creatures to start with anyway - either as eggs or microscopic babies or just well-camouflaged things - but if I make a concerted effort to, at the least, sieve things first, would that likely be enough to give the bacteria time to establish without too much pressure? I have what feels to be a thousand pot plants in the apartment already, so having a particularly watery pot plant for a month or two is perfectly OK by me.

Finally - to clarify - if I go ahead with this, and assuming I find an acrylic tank (great suggestion, thank you!), a cooling system I can afford/that'll fit the tank, and that I can seed the tank with straight seawater, do I need a mechanical filter, or just an aeration method - e.g., a bubbler or fan?

Feeling super excited about this already, actually, even with potential hurdles!