Re:New BioCube 29

Pete Giwojna

Dear JoAnn:

No problem, JoAnn – the 29-gallon biocubes are very well-designed, well-built aquarium systems for their purpose (reefkeeping), and they can be used successfully as seahorse tanks when modified to moderate the water flow and replace the lighting system, if overheating should become an issue. If you can switch to a smaller water pump, that would be one approach to preventing the water currents from overpowering the seahorses; another option is to use the same water pump but to attach a spray bar return, which will do a fine job of diffusing the water flow.

Regarding the 29-gallon biocube, JoAnn, as you know, they are designed primarily with reefkeepers in mind. As a result, they typically provide the powerful water currents and high intensity lighting, which live corals require in order to thrive. That can sometimes make the biocubes a bit problematic for seahorses, since they do best with moderate water currents and relatively cool water temperatures. Tropical seahorses such as Mustangs and Sunbursts (Hippocampus erectus) are most comfortable with stable water temperatures in the range of 72°F-77°F, and they can begin to experience heat stress and associated health problems when the water temperature approaches 80°F or above for any length of time.

I don’t know which brand of biocube you are using, JoAnn, but the older JBJ nanocubes and biocubes are notorious for overheating. You mentioned that you didn’t think overheating would be a concern in your case, so I’m thinking that your biocube is not a JBJ, which would be a good thing.

As you know, you may need to moderate the water flow in the biocube and take steps to prevent it from overheating, in order to convert into a suitable habitat for seahorses, JoAnn. I’m not sure which brand of biocube you have, so I’m going to guess that it’s a 29-gallon Oceanic Biocube, which is one of the most popular of the biocubes that are currently available…

I am familiar with the specs on the Oceanic Biocubes, although I have never used one or kept seahorses in one of them due to the drawbacks I mentioned. But I would be happy to give you my impressions of the 29-gallon Oceanic Biocube and my thoughts regarding its suitability for seahorses, JoAnn.

The wet/dry filter is a plus. When it comes to external filters, wet/dry trickle filters are probably the most desirable units for the seahorse keeper . They are top-of-the-line units that feature a thin film of water trickling over filter media with an ultra-large surface area, thereby allowing maximum air-water contact. This provides excellent oxygenation with efficient offgassing, which is very important for seahorses. It helps keep dissolved oxygen levels high, CO2 low, and effectively prevents gas supersaturation, which can sometimes contribute to serious problems (e.g., gas bubble syndrome) for our aquatic equines. As an added benefit, wet/dry trickle filters can also provide remarkable biological filtration, which can give you a real nice edge by further increasing your carrying capacity and boosting your margin for error accordingly.

I don’t know how powerful the water pump that comes with the 29-gallon Oceanic Biocube is or how many gallons per hour it puts out, but I would be happy to go over my usual guidelines regarding water movement in a seahorse tank with you, JoAnn. In general, the filtration system for a seahorse tank should turn over the entire volume of the tank a MINIMUM of five times per hour, so if the water pump for the Oceanic Biocube isn’t pumping at least 150 gallons per hour, then the system may actually be undercirculated.. It’s difficult to quantify the water flow beyond that because the optimal flow depends to some extent on the dimensions of the aquarium, particularly the height, and largely upon what type of water return the filtration system uses. For example, if the filtration system features a waterfall return or a spray bar return positioned above the surface of the water to provide better surface agitation and oxygenation, both of which effectively diffuse the discharge from the filter, you can easily use a water pump that turns over the entire volume of the tank 10 times per hour (or even 20 times per hour under certain circumstances) without generating too much turbulence or water flow for seahorses.

The Oceanic BioCubes are nice aquarium systems with a very efficient filtration system, but as I mentioned, like all of the nanocubes, they are designed with reef keepers in mind and have strong pumps that produce strong water flow and high turnover rates. The output from the pump often needs to be toned down a bit so it doesn’t overwhelm the limited swimming ability of Hippocampus, if you will be using a Biocube as a seahorse tank.

One good way to accomplish that is by adding a spray bar return positioned above the surface of the water to provide better surface agitation and oxygenation, which will effectively diffuse the discharge from the filter, allowing you to maintain a relatively high turnover rate without generating too much turbulence or water flow for seahorses. For example, this is how Estefano recommends modifying BioCubes and nano tanks to make them more suitable for seahorses with regard to the water flow:

<Open quote>
I recently bought a nanocube 24 (for a different reson other than a seahorse) but here are some of the recommended upgrades I would strongly consider if I were to house seahorses in this setup…

1) skimmer – Sapphire aquatic is comming out with a very high quality venturi skimmer that fits perfectly in on of the back compartments of the biocube. check; then click on skimmers, you will see the biocube29 skimmer there. there are others available, however this is one of the top quality skimmers out there.

2) SPRAY BARS!!! very important, all these nanocubes have very powerful pumps that are designed to turn water over 10-15 times per hour, as you may have read from previous recommendations from Pete you will know that this is not suitable for seahorses, adding spraybars (from loc-line, 1/2 inch; available at is a very good upgrade. they also have a check-valve available which you can use to slow down the water flow.

3) UV sterilizer – CADLIGHTS has created an in chamber UV steralizer I would strongly consider adding to a setup like yours. go to and click on the UV sterilizer from the list, its only $55 and a really nice upgrade for your new tank.
What I would recommend you do is the following:

Go to your local fish store and buy a Mini-jet 606, These pumps have a flow controller built right into them. They are rather inexpensive and readily available in every fish store out there.

This is the link of the pump so you know what to look for…

As a long term solution you should install some spraybars, I must advice you that you will need to sand down the original nipple that comes with the biocube in order to make the spraybars fit. Its really easy and only takes 5 minutes with sanding paper.

Here are the links of the spraybars so you know what to look for…

and the elbow you will need to make it go across the top…

and the regulator ball-valve…

I hope this help,

<close quote>

As for the lighting system, metal halide lighting used to be standard for most biocubes, and, unfortunately, in addition to producing high intensity lighting the metal halides also generate a lot of heat. Nowadays, many biocubes are available with compact fluorescent lighting or even LED lighting, which is a nice improvement that goes a long way towards reducing overheating. Compact fluorescence are a good choice for seahorses, JoAnn. They shouldn’t be too overpowering, yet they will put out enough light to maintain a healthy growth of macroalgae or sustain soft corals that are safe for seahorses. The blue lunar "moon lights" are also a nice feature that the seahorses should appreciate.

In short, although I have had no personal experience with the Oceanic Biocubes, based on their overall design I do think they would make an acceptable aquarium for seahorses as long as you take into consideration the factors we have discussed above, and consider modifying the tank by installing a spray bar return to diffuse the water flow.

The new inserts for the biocube are excellent, JoAnn, with plenty of room for various chemical filtration media. Of the two possible configurations shown in the illustration, I would favor the fuge basket over the Tunze protein skimmer, since the pump for the protein skimmer could contribute to overheating of the aquarium water.

It’s good to see that you will be using live rock, and the combination of live rock with artificial corals and gorgonians can be very effective in creating an ideal environment for the ponies.

In any case, JoAnn, I will be working with you personally every step of the way from now on, through our ongoing correspondence, until your 29-gallon biocube is ready for seahorses and you are well prepared to give them the best of care, regardless of how long that may take. It’s going to be a pleasure working with an experienced marine aquarist who is a conscientious aquarist, Joan, and I know that with your background your seahorses will receive plenty of TLC.

Pete Giwojna, Ocean Rider Training Program Advisor

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