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not another new tank thread- SUBSTRATE For Octo-bimac POLL

Nov 1, 2003
hi- first time on tonmo.long time reef central junkie. i have already read all the reccomended reading and am fairly confident i can keep a bimac.

one thing i do have a question about is the choice of substrate. well not the choice of substrate i guess but the depth of the sand bed. i gather the best substrate is a smaller particle sand bed ie southdown or pure carribean aragonite{what i use in my reef 55, 5 in deep- have had good sucess with this so far}

is it better to have an inch deep bed that you vacumn to remove waste or a live dsb{6 inches deep} with all fauna it provides and or accomodates?

do the octos produce solid waste that could be vacumned?

keep this thread alive!
Hi and welcome to TONMO.com!

Colin has written a lot about why a deep sand bed is not desirable, which you can find by searching past posts.

But there's this aspect, too - Full grown bimacs take charge of their environments and make lots of changes to what you've set up. My bimac, Ollie, has pitched out sand from his den and dug out a wide area right down to the glass bottom. (I even saw him using his mantle as a basket and haulting lots to his den entrance to dump out!)

I think almost all of us are using 2 inches or less for our sand beds, and most are using fine sand or aragonite.

As for vacuuming, I used to do that, but Ollie keeps everthing so stirred up that little is left to vacuum - most floats off and through the filters. Octo waste comes in long strings and it's easy to catch these and remove them, if you're around. Otherwise, they often float off and down the overflow and all that reach the sand are quickly consumed.

Hope this is at least a start on answering your questions.

I Have to say that it does vary with species too. Our large P. cordiformis has bare rock with a "pool" of coarse gravelly sand this is mainly for the crabs to bury in.

Our Midgets have deep sand (around 20- 25cm) they don't disturb it much but occasionally like to burrow into it.


i still have some of the carib sea aragonite-its the sea floor special grade reef sand. this should be ok...right? less coarse then CC and ive read you can use CC with bimacs..so this should be perfect
OK.. I have a question. Is substrate neccesary or can a bare bottom tank be successful? The reason I ask is that there seems to be a new shift in though on Reefcentral concernign barebottom tanks, or the use of Starboard (Plastic Cutting Board Material) on the bottom of the tank. Starboard protects the glass from liverock, and helps spread the weight of the rock across the entire bottom of the tank. The use of SB (StarBoard) allows the detrus to be sucked into the filtration, or makes it easy to clean the tank weekly by vacuming the tank out. An aditional bonus is that the SB is available in a wide range of colors.

Preliminary reports are that the tanks are thriving, and water parameters are good. Coralline is attaching to the SB, and apparently corals are attaching to it without any problems as well. I think in theory a SB bottom tank would work, I'm just worried that the Octo's would need more stimulation , than Live Rock on a cutting board in the tank.


Hi Vzvicious (hope I spelled that right!),

Welcome to TONMO.com!!

One way bimacs hunt is to run the tips of their arms through the sand, probably to find crabs. My bimac has played in the sand a lot, so I think from that standpoint it would be a loss.

Interesting concept, though. would like to hear some other views on this.

I think that the main difference we have between SPS tanks/reefs and octo tanks is that corals etc dont need any enrichment of their environment... IE something to do.

While i agree that sterile tanks may be easier to clean its going to make it a very unnatural glass desert for an octopus and therefore lead to security and enrichment problems...

at least put a cm or 2 of fine sand in there, it's still easy to clean.

Not dissing cnidarians but octos have active brains!!!
That was my thinking as well. I think chemically the bare bottom would work like a champ. However, the big drawback is the "entertainment value" added by sand. I've been following Tonmo for a year researching the proper setup. I'd love to try this setup, but not for my first Octo.

Perhaps in the future I'll set up two tanks one BB and one with 1" of sand and connect both tanks to a central sump so there isn't an issue with water parameters. Then observe the Octo in each tank........

perhaps BB is best left to Reefs and Cuttlefish.......
LOL i'd disagree about BB for cuttles too LOL they use the sand more than octos.. has to be fine sand though

cheers, keep us up to date
My cuttles always slept with sand over their bodies, they'd sit and throw it over by beating their skirts 8)
One depth does not fit all

A sand bed good for one species is not necessarily good for another. Depth, grain size and composition all have to be selected to fit the species as well as the type of system.

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