Reef Zones

[Masamune]

I've been poking around the forums after taking a break from reefing and was inspired by Giga's mangrove tank(s). I also watched a video someone else posted (

) which was filmed in a mangrove lagoon which prompted me to think about a tank concept.

 

 

Simply put, I was wondering how one could create a tank that replicated several different zones of a coral reef. One end would have mangrove trees growing on top of live rock. Next would come a small seagrass area, followed by a "patch reef" with small pieces of live rock + corals, another small seagrass area, a shallow forereef area, then a barrier or reef crest area with a large rock island/wall. Refer to the top image in this picture.

 

The side of the tank with the reef crest/barrier reef would have a powerful powerhead (like an MP 10 or larger, depending on the size of the tank) operating on wave mode or with a wavemaker. The large rock island/wall + corals would absorb the impact of the powerhead and act as a buffer, softening the flow to the rest of the tank. Smaller powerheads might be added along the course of the rest of the tank if needed. The general idea being that the reef crest/barrier area has the highest and most turbulent flow while the mangrove area has a more gentle flow. The mangrove side of the tank would have the overflow leading into a sump. The return would be of on the opposite side (the reef crest side).

 

Some questions and issues came up while I was thinking about this though:

1. Would it be possible to do something like this in a tank less than 70 gallons? What kind of dimensions do you think would work best (I was thinking something long and flat, like a custom 60x16x16)

 

2. Would it work to have different lighting in the different areas of the tank to replicate deeper water? (IE: low - medium light in the mangrove area for the shade from the leaves, bright light for the seagrass, patch reef, and forereef, then low - medium again for the deeper "barrier" area?)

 

3. Generally speaking, how could you differentiate the reef zones by using livestock? (softies, sponges, etc... in the mangrove, montiporas in the patch/forereef areas, acros/favias on the reef crest?)

 

4. Obviously a normal lighting fixture wouldn't work. Would it be prohibitively expensive to use multiple lighting methods (not just for purchasing cost but also power bills) for the different zones?

[seabass]

1. Would it be possible to do something like this in a tank less than 70 gallons? What kind of dimensions do you think would work best (I was thinking something long and flat, like a custom 60x16x16)

That's 66.5 gallons. I think it's basically possible, but I'd think it would be pretty difficult to satisfy each area without affecting the others. You'd need to provide enough nutrients for the plants, but retain overall water quality for the reef areas (like for SPS corals).

 

2. Would it work to have different lighting in the different areas of the tank to replicate deeper water? (IE: low - medium light in the mangrove area for the shade from the leaves, bright light for the seagrass, patch reef, and forereef, then low - medium again for the deeper "barrier" area?)

I would probably use pendant lights to customize the areas and transitions, as opposed to one long fluorescent T5 fixture.

 

3. Generally speaking, how could you differentiate the reef zones by using livestock? (softies, sponges, etc... in the mangrove, montiporas in the patch/forereef areas, acros/favias on the reef crest?)

It would work better in a huge tank, so that the fish could develop territories in their chosen zone. I'm not sure that they will keep to one zone in a relatively small tank.

 

4. Obviously a normal lighting fixture wouldn't work. Would it be prohibitively expensive to use multiple lighting methods (not just for purchasing cost but also power bills) for the different zones?

You could use a MH fixture for higher intensity areas, mixed with other types of pendant lighting. However, I'd probably try to use similar LED pendants (or even PAR38 bulbs) spaced to illuminate the zones as needed.

 

 

I'd probably use multiple tanks set behind a wall (with dividers to help hide the tanks' sides). This would allow you to confine the livestock in each zone, and to provide specific needs (nutrients, calcium, etc.) for each zone.

 

Maybe like three 24 to 30" long tanks. To help with the illusion, you might place rock and a similar coral (even a similar fish) in the adjacent tank so it appears to flow into the adjacent zone.

 

Edit: I bet you could even pull it off with just two tanks. If you want to keep it to 60" long (two 30" tanks would work perfect). Also, you could build the dividers as part of a custom stand (so it wouldn't have to be a behind wall tank).

[Masamune]

Would the mangrove/seagrass areas not count as a sort of in-tank refugium? If not I guess there wouldn't be any harm in having a display "fuge" with the mangroves, macros, and seagrass and have another tank with a small outcrop on one side (patch or forereef) and the "reef crest" on the other.

 

As for the livestock, I wasn't so concerned about inverts and fish cheating by changing zones but rather what types of corals and such to have in the different mini-zones to complete the effect.

[seabass]

I don't know if you could easily pull off a seagrass bed along with SPS corals in the same tank. It is a delicate balance of providing enough nutrients for seagrass to survive, a deep enough sand bed for their roots, and the sand bed having to deal with all the organic matter of decaying roots. Not to mention that SPS wants pristine, low nutrient water.

 

I'd love to see you successfully pull it off, but I'm cautiously pessimistic about the possibility of long term success. To do it in one tank, I'd probably pass on the seagrass bed. Plus, if successful, the grass would quickly spread into all zones.

[Masamune]

Upon further research it would seem that this idea might not work at all. In addition to the nutrient issue you mentioned one would also have to be concerned about allelopathy.

 

"For the Sargassum spp. and that particular coral IN THE OPEN SEA WHERE DILUTION OF THE ALLELOPATHIC SUBSTANCES WOULD BE ALMOST INFINITE, it requires direct contact. As there are eight different mechanisms employed by algae as allelopathic competitors, it will sometimes depend on the coral and the algae.

 

However, in a closed system where there are high population densities of the algae and the coral when compared to the sea (very few locations in the ocean have densities where algae tke up 25% of the total volume of a region), and in 185 or so USG of recirculated water, substances like this tend to accumulate, even with good skimming and carbon, to many MANY times the concentration of that found in the ocean...

 

We will find that instances of this type of competition can be multiplied many times both in terms of concentrations of triggers or toxins and in consequences of the releases of allelopathic toxins when we talk of closed systems and the accumulations of these substances."

 

-Exceprt from a post by tdwyatt in this thread (http://www.thereeftank.com/forums/f6/to-chaeto-or-not-to-chaeto-does-macroalgae-for-nutrient-export-inhibt-sps-growth-108771.html)

 

Allelopathy doesn't seem like it would be too big of a problem in a normal tank with a planted fuge (from what I gathered from that thread) but with as much macroalgae and such that I was thinking of keeping in the mangrove area it might become an issue.

 

 

I guess it might be better to have a planted tank with the seagrass, soft corals like xenias and kenya trees (maybe?), and other filter feeders as the "mangrove" zone. The second tank would start with the patch reef and end with the crest or reef wall zone with the fancy-pants sps.

[MeepNand]

It would have to be huge, and you would have to employ multiple surge tanks to make waves. An mp10 might do it, but 3 or 4 surges would be better.

[Masamune]

I wasn't planning on making it realistic. I was just thinking of making a mini representation. In actuality I may just go for 2 tanks; a shallow cube with a mangrove planted island in the middle with non-photosynthetic stuff, maybe some macro's like halimeda, etc... and a second tank, maybe a 45 long, to be the reef area.

[MeepNand]

Would the tanks be connected or just be next to each other?

[Masamune]

They might just be next to each other or perhaps connected by a sump.