A Low Maintenance/self Sustaining Saltwater Ecosystem





Introduction: A Low Maintenance/self Sustaining Saltwater Ecosystem

About: My name is Paul Roncal and I'm the founder of PJ reefs. I have a degree in biology from the University of Texas at Austin. The living organisms of the ocean, in particular corals, have always fascinated me. ...

I have always been fascinated with miniature ecosystems. When I became interested in saltwater aquariums, I was always attracted to the smaller systems. At first many would say that it was difficult to maintain a small aquarium. After experimenting with many setups I came up with a setup that is easy to maintain and self sustaining for long periods of time. Here are the instructions in how to create one.

Step 1: Materials

The most important component of the build is the PJ reef lamp. This lamp can be purchased at PJreefs.com. It includes special LED lights that allows for corals to grow and thrive.

The other required components are a:
- Hand towel
- Water pipette
- Tweezers
- Gel super glue
- Saltwater
- Live rock
- Corals and macro algae

Optional items if you want to make your own saltwater,
- Stirrer
- Saltwater mix
- RO/DI water
- Refractometer
- Small pipette

Step 2: Preparing the PJ Reef Ecosystem Saltwater (optional)

Saltwater is readily sold in local fish stores. The only problem is that quality varies from store-to-store. PJ reefs will be offering their own saltwater already made at their website.

Here are the steps in making your own saltwater
1) Purchase RO/DI water.
2) Mix saltwater mix according to the saltwater mix label instructions.
3) Dissolve saltwater mix in the RO/DI water.
4) Check with refractometer that the water is at 1.025 sg.
5) Clean refractometer.

Step 3: Creating the Ecosystem

Next step is building the PJ reef ecosystem

- Add the live rock to the jar.
- Remove the corals one by one from the storage container.
- Add superglue on the back of each coral or the rock they are attached to.
- Attach corals to the rock.
- Put 2 macro algae in the system.
- Make sure that everything is attached and placed correctly.
- Check that water level is at the height of jars cover.
- Adjust accordingly.

Step 4: PJ Reef Ecosystem Requirements

Now place PJ reef ecosystem on the lamp. There are four maintenance requirements to keep a successful PJ reef, they are:

1) Maintain temperature between 70°-83° Fahrenheit. No drastic changes.
2) Saltwater change every 3-6 months, preferably 3 months.
3) Addition of pure water every month or so to compensate for evaporation.
4) No over addition of corals and animals.

The ecosystem will change and you will see many of the live rock inhabitants begin to reproduce and estabilize the ecosystem.




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Wow that's not bad at all! Wish this was available a year ago before I threw $400 into my nano. Great idea!

No fish can be kept. It mainly for the micro fauna found in live rock. Also, we are developing instructions on maintaining smaller system with certain species of fish.

The kickstarter page he linked to is defunct. Although it pretty much looks like a jar and an LED lamp.

1 reply

Hi JesseM18, we got funding for the design through kickstarter 3 years ago.

The Instructables is to give other people ideas so they create their own. The lamp that is used in this Instructables was a early prototype, the one we sell in www.pjreefs.com is machined using aluminum and electroplated with color.

You can substitute this lamp with other lamps and LED available.

do you still have it alive ? if so. how did you did it without a filter or water pump???

hey Davef2, thank you so much for the ible! It's very rare to see one of this quality, that seems to be informative, but in the end, turns out to be an infomercial... Keep up the great work, it's unbelievable that its possible to buy some live rock, which is already cultured, stick it in a $.50 cent jar, then buy coral, that someone else spent the time to raise, and only pay $100 for the "whole setup". Thank you again for your contribution to this DIY community. Only one problem I see at this point, is there a number you can post for free so that people can purchase these $100 mason jars? I'd hate for you to lose any commission opps...

This instructable reads like a sales pitch for PJ reefs. I personally don't see this working with NO water flow, but anyone can buy a glass cookie jar and a full spectrum LED bulb (look for 6500k to 10000k on ebay) and try it on their own. Live rock can be purchased at most mom and pop fish stores.

2 replies

The Instructables was made for people that like to DIY things, and was not intended as a sales pitch, just straight instructions on how to make one.

It should be noted that you need to use Super Glue >GEL<. Not plain super glue. Super Glue Gel has Cyanoacrylate that give it the ability to cure (dry) underwater and will not poison your inhabitants.

The lack of any flow greatly disturbs me as well. The live rock acts as natural filtration as the water flows through the rock. No flow = no real filtration. Yes, it could be argued that there's SOME filtration as the bacteria on the surface interacts with the water in direct proximity to it, but it will not filter the bulk of the water.

Source: I'm the vice president of the Chicago Marine Aquarium Society.


1 reply

Hi Dave, I documented my idea in nano-reef.com a few years ago and has quite an interesting story, here is the thread. The original aquarium is still alive and gives me a reason to continue with PJ reefs.


Looks awesome and easy - I'd like to point out you should never really have any fish in a setup of this size, but you can get lots of extra animals who come along for free when you get live rock - some are really interesting to see! :)

Hi! I would love to buy one of these , I have always wanted a saltwater aquarium but I don't have the room or time for a huge one! Do you have to have experience with saltwater aquariums to keep one? Is it hard to maintain? I have only kept freshwater aquariums. What do you feed the coral, animals?

thank you!

Very neat idea. I have one concern/question. We know that corals rely on water movement to supply them with oxygen and food so what does this system do about water flow and gas exchange?

1 reply

I'd like to know about this also.

Sweet, now the fun part, trying to find a way to build one myself for cheaper...

How much did the cylinder tank and lamp cost?

1 reply

Hey jamob, it cost $100.

The live rock and corals are aquaculture.