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Tidal/Surge tank setup

Joined
Aug 13, 2009
Messages
1,740
Hello everyone. It's been quite a long while since I've been on here. I've been out of the hobby for about a year or two for various reasons, and I've decide to get back in again. I've sold all of my aquariums (yes including my 250g :cry: ) accept for two 10g's and a 1/2g hex. The hex is occupied for a FW guppy for my son, leaving the two 10g's. So to save money I'm starting my project in one of them. I've always been fascinated by tidal ecosystems and wanted to create one (as closely as possible) for the longest time. I've been looking up ideas on how to build DIY rock formations/walls, surge/switching current devices, and filtration systems. My plan is to make a rock wall with bulges, shelfs, and caves, along all three sides. Along the middle of the back wall I will place the pumps and filtration system. The jets will be placed in each back corner aimed at their opposing corners across the tank. The center will be open with a bare sand bed. Though I may place a few LR rubble for debris along the sand bed. Since I'm doing everything internally I'm not going to worry about rising and falling tides with a reservoir or anything like that. I'm just going for the strong shifting currents at this point being that it's my first tidal tank. I'm using a 3/4" SCWD and 900 Maxijet for circulation and switching current. The rock that I want to use (as I have not yet purchased any rock) is referred to as "dragonstone" by the person who sells it. The idea that I'm going with is kind of a volcanic/alien world here. I think I can pull of a really creative and artistic look with the lighting that I have and this rock. My concerns are being that this is a small (10g) tank, with a strong alternating current, and the walls are covered with volcanic rock, would a setup like this be octo friendly? I'm pretty sure that common sense dictates no, but I thought I'd run it past the rest of you who are more knowledgeable and more experienced than I. Though let me say that this is not a temporary octo tank. I am building this with the intent of a reef/invert tank. But I was thinking I could use it as a grow out tank for any future octopus. Questions, comments, concerns,..improvements?
 
Thank you for the warm greetings. I must say this new format is going to take some getting used to. :smile: I'm not actually going to start cycling and stocking this tank until I move back to Texas. I thought I'd get a head start on the criticism though so I can have it tweaked and ready to go for after the move. After I get this little project perfected and out of the way I plan on duplicating it in a larger and more ceph friendly version. I was thinking between 55-125g. But that's years (and much groveling to the wife) down the line.
 
IMO, a 10 gallon tank is too small for even a merc but GHolland had luck raising hatchlings in a couple of very small tanks. Keeping one in that tank is likely to be a problem if you are lining the walls with rock. If "dragonrock" is actually volcanic, the general thought it that it will continue to outgas sulphur and pollute the water but I have never experimented with it.
 
I was concerned with whether or not it would altar or affect the chemistry of the water. The guy sells it for FW planted tanks mainly so I was unsure of the effects of using it in SW. I've never come across sulfur in aquarium water. How toxic is it? What about the surface texture though? Would jagged rocks like this be too rough/abrasive for an octopus? And as far as the size goes, you don't think it would be a suitable 'grow-out' tank for a short period (maybe a month or two) until it would be large enough for say a 55-125 gallon? I know when I had one octopus that was about the size of my thumb nail when I first got her and I had to keep her in a critter keeper floated inside the tank until she was large enough to release into my 110g.
 
Putting a small tank inside a large tank is not the same as using a small tank. It is the water quality of the small tank that is the concern. Several people have worried about abrasion but I don't know of any reported problems.
 
True,..water quality is harder to attain and maintain as the volume of water decreases. Oh well it was just a thought as using it for a grow out tank. If I did this in a larger system, do you think having strong alternating currents would be problematic for an octopus? As a side note I'm only using the "dragonstone" in the 10g project and would be using more natural marine rock for the larger setup. I know they can be found in tidal areas where the current can be quit strong, but ethically speaking while we try to replicate a natural environment we should strive to make life easier on them not harder correct?

This video is the kind of tidal environment I want to recreate in an aquarium. You can see how strong the current is that I'm keep asking about at around 1:45 minutes into the video.
 
My brain says an octopus, in that kind of turbulence, would take shelter and rarely be seen but I don't know of anyone who has tried it. The movement would likely keep the water cloudy, not usually desired in a display tank, but would seem to be a plus for moving waste to a filter. The only comparative I have is the negative reactions my octos appear to show when I clean their tanks. They don't hide as I would expect during a constant motion but come out and try to (or so it appears) stop me from disrupting their environment. Constant particles in the water might affect their gills but I have never read a paper that suggest this.
 
Those are two really good points (hiding/gills) that I hadn't even considered. To combat cloudiness caused by the turbulence, I'm working on a custom sand filter. Not sure how well it will work, but that's why I'm doing this in a 10g first. I'm hoping that the high volume of water being pushed around will yield a high turn over rate. I want to place the jets in the back rear corners aimed slightly up to keep most of the turbulence in the water column. This in hopes to not push the substrate all over the tank like a dust storm and to help keep debris and detritus in the water column to be filtered. There will be several layers of filtration (pre-filter/sand/pre-filter/carbon/pre-filter/nitrazorb&phosban/pre-filter) and I'm hoping that it'll polish the water pretty nicely. Everything is still in the planning stages right now. I'm stuck on a dilemma with the height restrictions of a 10g and the over all height/length of the maxijet/scwd combo. I only have 11" to work with and the pump/scwd take up most of that. So to put in the kind of filter I want is gonna take some finagling.
 
I received a reply from the man selling the "dragonstone" and this is what he said.

It is Basalt Scoria, it is definitely lava rock. There are many different kinds and all do not release sulfur. Scoria is 60% silica, magnesium and iron. But the minerals are not reactive they are bonded to the silica and do not alter water chemistry. The rock is completely inert. It is like glass or silica sand. Now what affects do high concentrations of saltwater have on the rocks? IDK. I haven't used it in saltwater, but want to! I really doubt it will alter your chemistry. Now all of the dust and sediment throughout the pores might! That's why you would really have to clean it. I mean really clean it. Why not just use live rock? I would.
 
My best guess is, If it is much like glass, even with the gas holes, it is not likely to culture bacteria well. It would be interesting to see if it works the opposite and actually stays clean in a marine environment, something that would be welcomed for some FOWLER tanks but I am not sure what out-gassing tests could be made to be sure it was not poisoning the water.
 
Well if he ever gets some of this rock in stock before winter sets in over there in Colorado I'll definitely order some and see how well it sustains basic damsel fish. How could I test the water for toxic gases?
 

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