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How To Choose A Pico Reef Tank

There are many varieties of small aquariums that can be used as a pico reef tank, but there’s nothing quite like growing a reef in a flower vase or cookie jar.

To top it off, you may already have something at home that you can use. Or you can ask a friend or family member if they are willing to part with one. That means one less expense on hardware that you can use towards purchasing corals.

Let’s look at some of the pros and cons of using a cookie jar and a flower vase.

Cookie Jar (Free - $20)

Pros:

  • Heat is retained longer compared to a thin glass vessel. Slower temperature swing down (i.e. 82f to 78f). This also means less strain on the internal heater.
  • Resistant to cracks and chips.
  • Easier to access the internal areas compared to a really curvy vase.
  • Difficult to knock over.

Cons:

  • Thick glass dilutes viewing crispness. The jar I chose has 2 vertical seams where the jar was melted together and the glass has some sort of glaze to it.
  • Glass used for cookie jars tend to have a lot of imperfections. I spent 15 minutes going through all the jars in the store until I found the best one.
  • During the summer months heat can build up quickly and takes longer to cool down.
  • Using a power head could create a whirlpool effect inside the jar.
  • Difficult to seal the top of the jar compared to a flower vase.

Flower Vase (Free - $15)

Pros:

  • Aesthetically pleasing to the eye!
  • Easy to seal. Helps prevent water evaporation which helps maintain salinity levels and reduces salt creep around the top of the vase.
  • Usually smaller and easy to transport (new location or cleaning).

Cons:

  • Many flower vases are made of thin glass that are prone to chipping and cracking (especially when placing or moving live rock around)
  • Thinner vases typically have a small base foot print. Even with a lot of live rock inside the vase to weigh it down, it could be easier to accidentally knock it over compared to a cookie jar.
  • Smaller necked vases can make it difficult to take out or place new corals, live rock, and hardware.

The cookie jar I’ve used has a short neck and doesn’t gradually narrow. This makes it difficult to seal, but it’s not impossible. There will a need for some air exchange with both vessels since we will be pumping air underwater to create flow. If it was totally sealed, something would blow eventually.

I would have bought a flower vase if I had found one, but I didn’t. However, I’m still very happy with my cookie jar and both options can still achieve the same results.

The Best Lids For Vases And Jars

The purpose of a lid is to minimize water evaporation and keep the waters salinity as stable as possible. The way this happens is that water will evaporate, condensate on the underside of lid, and eventually drip back down in to the water. Later in this setup series I will talk more about salinity, evaporation, and specific gravity.

The best lids for our purposes are ones that are transparent (glass or plastic):

  • Bowls
  • Plates
  • Plant Saucers - cheap and can be manipulated easily

Vase Lids

As I mentioned, a flower vase has a great neck to be able to invert a bowl, plate, or plastic saucer to create a lid.

Pico Reef Vase Lid

As the neck of the vase gets narrower it prevents the “lid” from falling all the way inside the vase. It creates a pretty good seal for evaporation and also means that salt creep will be limited to the neck and edges of the lid.

In this case you could call it a day and simply rest the lid on top of the air line and heater power cable. This would leave a small gap, but that’s okay.

Alternatively, you could drill a hole for the air line and cut a notch for the heater cable to allow a better seal. If you’re electrically competent, you could drill a hole for the heater cable as well by dismantling the heating wiring to fit through the hole and then reattach it.

vase drilled holes

However, this can be extremely dangerous and takes away some of the simplicity of setting up this pico tank.

Cookie Jar Lids

A challenge with most cookie jars is that their necks are usually short and don’t narrow like vases. So it is very difficult to create a seal using a glass bowl or plate.

Using a flat piece of acrylic on the top of a cookie jar will not create a good seal. Salt will creep out between the top of the jar and the acrylic. Moisture will follow this same path and either evaporate or condensate at the edge and run down the side of the jar.

Here is a picture of an acrylic lid that doesn't seal well and will have salt creep issues:

acrylic lid no seal

I’m currently testing some ideas to make a better seal for the jar, but for now, a clear plastic plant saucer is doing the trick.

plant saucer lid

I’ve trimmed a 7” saucer to fit a 6” hole so that it needs to be bent a little to fit inside the top of the jar. The saucer is trimmed to 6.1 – 6.2” to allow it to remain in the neck by outward force from the plastic trying to go back to its original shape.

It takes a little bit of care to squeeze and manipulate the plastic in to the hole. It's easier when the notches are cut for the tubing and cables as seen here:

plant saucer lid air line heater cable

I’ve also cut the plastic at the back to allow space for the air line and heater power cable. It’s not pretty but it’s doing pretty well in terms of keeping evaporation down and salt from creeping around the edges.

How Do I Decide?

To be honest, both are great choices and can get the job done.

I decided to use a 2 gallon cookie jar because 1.5 – 2 gallon flower vases were difficult to find during the winter season. I would have preferred to use a flower vase for its aesthetic appeal, but I ended up with a cookie jar and I’m happy with the way it’s turned out.

Which one is more appealing to you?

All Vase Images by Brandon Mason (The History Of Pico Reef Biology)
  • November 28, 2015
Click Here to Leave a Comment Below 8 comments
Jody - April 1, 2016

Hi, after it is setup with the sand and rock, how long before I can put any thing in it? Does it have to cycle like a big tank?

Reply
    reefjar - April 2, 2016

    Hey Jody!

    In my experience, if you’re using live rock that hasn’t been sitting out of water for long you should be able to add corals almost immediately. But before adding any life, I recommend running your pico for a few days to a week to make sure that your parameters are stable (salinity and temperature).

    Small cycles can still occur as you add stuff in to the pico, but the feeding/water change schedule helps prevent waste from creating negative water quality parameters.

    Reply
danny - December 18, 2016

Scine these reef jars seem to require more frequent and larger water changes than a regular reef tank, is there any point it testing the water? Do you ever test and if so what are you testing for? thanks.

Reply
    reefjar - December 28, 2016

    Hi Danny,

    Since I do 100% weekly water changes, I only test for SG and Temp. I would recommend testing the water before and after if you are dosing. The general rule I have is: if you aren’t testing, you shouldn’t be dosing. Because you really don’t know what is what and will probably throw something out of wack.

    So far I haven’t had any issues with just water changes. The key has been to do them consistently.

    Hope that helps!

    Reply
Jacob Terry - January 26, 2017

Could you help me decide which way I should go for a nano? I’m torn between making a cookie jar based off of this site or a 3 Gallon mainland contour. The contour has a pump and back compartment where I could place a heater and a lid. It would require less DIY. Although there still isn’t much DIY with the jar. I plan on using the same lighting you use. I plan on it being a coral only with possibly of a small (2 snail 2 hermit crab clean up crew). The reason I’m unsure of which to do is evaporation. This seems like ones of the more important factors for stability in nano/pico reefs. The jar seems to have little to no evaporation. The contour has a glass lid, but with a pump/filter there is exposed water surface. Any advice?

Reply
    reefjar - January 29, 2017

    Hey Jacob,

    Great question! There are a lot of factors that contribute to evaporation, as you seem to already know. A big factor where I live is that the air is very dry naturally. So having a jar with a tight fitting lid is perfect!

    However, to give some perspective, I recently started a Fluval Spec V SPS dominate system, 5 gallons. I had a piece of acrylic as a lid across the main portion of the tank, and the back chamber exposed. I was going through about 1/2 gallon of water per week due to evaporation.

    I’ve since removed the lid because I want better gas exchange since I don’t open the windows that often during the winter. Better gas exchange and gases present in the room etc. also affects pH levels. I’m using an auto-top off now because it goes through close to 1 gallon of water per week! I don’t have central air or anything so I expect it to increase during the summer months.

    If you decide to go the 3 gallon route, setup the system with water/pumps/lights and see how much water it’s losing per week. You may need to purchase an ATO if you don’t want to be topping off manually. I’m using the “Smart ATO Micro” that can be found on Amazon and so far it’s working great!

    I hope that helps,

    Justin

    Reply
Kaleb Spain - March 20, 2018

I have the same jar. Mine came with a glass lid. Did yours come with one? If so why did not use it? Thanks in advance!

Reply
    reefjar - March 27, 2018

    Hey Kaleb,

    My jar came with a metal lid, unfortunately. One thing that I would be concerned about with a glass lid is the thickness of it and how much light it’s letting inside the jar, especially with more light demanding corals. Even if it looks like light is going inside, some of the beneficial bands might be refracted away or blocked by a thick piece or rippled glass.

    You might also consider how it sits on the jar and where salt creep could work its way out and how you’re going to control evaporation.

    Just a couple things to consider from my perspective.

    Hope that helps,
    Justin

    Reply

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