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New octo tank ideas... recommendations?


Jan 27, 2004
I've been snooping around this site without logging in for over a year, though I haven't been posting, I _have_ been learning :smile:

I have a 29g tank, drilled, with a 20 gallon sump/refugeum combo. It has 4" of southdown sand in tank and refugeum, about 25 lbs of live rock, an aquaC (cheap!) skimmer, a few corals (mushrooms, zoanthinds, and a cabbage leather), and a few calurpa sp. macro algae in the tank. There's a 70w ushio 10,000k metal halide light over the tank, and a 55w PC light on the sump/ref. Tanks been running for a little over a year as a seahorse tank, it has tons of mysid and gammarus, a few hermits, and lots of bristle worms. The tank is quite stable, hasn't shown any ammonia/nitrate/nitrite in a year, temp is 76f, pH is 8.1, Ca is 340ppm...

I'm considering changing this tank over to an octo tank. Other than needing to add a glass top and screening the inlet/outlet to the sump, what would be needed to convert this little tank to an octo home? There's no cords/powerheads/etc in the tank, all the mechanicals are in the sump. Sealing the top ought to be easy, nothing in the way. How would you suggest covering the inlet/outlet pipes? Both are just 1" PVC elbows at the surface... just use a sponge over the openings? Is the little 70w metal halide too much light?

The tank has aptasia and flatworms, not so bad that they're taking over, but they're in there... would I need to irradicate them? How about the calurpa? Does it present any issues? If bristleworms are a problem, then I'd have to replace all my live rock, it's heavily populated with them.

I'm thinking of getting my octo from octopets.com, seems like a decent supplier, any personal experience with this outfit?

There's pics of the tank available at Blog - Greybeard's Rants under the photo gallery link. It's currently housing seahorses though... most of the pics are of the horses.

Any and all comments and suggestions are welcome... Sorry for the long first post, I been thinking about this for a while :smile:
Hi cmidkiff,
Welcome to TONMO.com!

Lots of questions :smile: My first concern is that this tank may be a little small for a bimac. Given our recent experiences, we know that some bimacs do get rather large and need at least a 50 gallon tank.

I won't try to answer all the questions, just hit the high spots. The lights are far too bright, you just need about a 30w fluorescent bulb. Yes, you need to cover and seal the tank, including power flow outlets, etc. Some people use a sponge, others cover outlets and intakes with netting.

Aptasia can sting an octopus, so needs to be removed - I had a big fight with it myself.

I hope you've had a chance to look over the Equipment List and Checklist articles (you find these by clicking on Ceph Care at the top of the page). They may give you some additional detailed information.


Thanks... :smile:

I have indeed looked over the posts regarding setup of a tank for octo's... the minimum size was shown as 30g, is there something new on this one? The 29 + the sump/ref gives me something like 40g capacity. I don't know enough to care so much about species of the octo, but I do want one that's more active during the day... any recommendations on a dwarf species? I'll review the suppliers list again...

I figured that the mh light was too much, but I thought I'd ask. At least it's gentle coming on, getting slowly brighter. I have several old normal-output florescent hoods around, that's no problem. I just love the shimmer effect that MH lighting give a tank.

Aptasia have to go... I thought as much, I'll start nuking them ASAP. Problem is, I've never been able to rid a tank of them completely. How 'bout the mushroom corals and zoanthids? Oh, if the light has to go... these will as well :frown: No use killing the corals off for lack of light.

Currently, I'm not running carbon on this tank (yeah, I'm another of those darn reef'ers...) but I was planning on adding a carbon cartrige to the sump inlet.

I've been looking, and I see some references to people not liking DSB's for octo's, but I haven't found the reasons yet... I'll keep looking.

Keep it comming :biggrin2:
Hi c,

The issue with the tank size is this - some people have successfully kept bimacs in a 30 gallon tank. But about 3 of us had bimacs that grew quite large, and I was afraid mine would outgrow her 46 gallon. She put quite a strain on my filtration system, too. (But she was quite a handsome, big friendly octo. ) This is why we're now recommending 50 gallon tanks as a minimum.

As for deep sand beds, I'll save that for Colin (he does not recommend them), but I'll just remark that my bimac moved all the rocks, dug down to the glass bottom and rearrnanged much of the sand, so it's not exactly like having a calm fish aquarium.

We feel the best octopuses as pets are the captive bred bimacs available from FishSupply or Octopets, and many of our members have or are successfully raising these octos. The other wild caught species are more "iffy" - sometimes you don't get what you've ordered, or the octo is adult and near the end of its life. (and sometimes it turns out fine) The dwarfs tend to live only 6 months, so not many people try to keep these smaller octos.

Welcome to tonmo.

Also considering your desire for the octo to be dinural would suggest bimac. Most pgymys are nocturnal.

Try kalkwasser in high concentration and inject them with a 14g syringe into your aptasia, (get the base full) prior to the octo being around and you should save your LR. Or you could always wash it under hot water. 8)

It has worked for me in the past.

Colin told me his method, which I've tried and it does work. It has the advantage of using only boiling water, nothing else.

Prepare a small pan of boiling RO/DI or distilled water.
Have ready several small syringes, the kind used by diabetics (buy at a pharmacy in the U.S.)
Fill the syringes with boiling water and inject the hole in the rock where the miserable creature lives. Better still, inject the creature itself. Empty the entire syringe.

This has about an 80% success rate!

If you already have an octopus in the tank, be careful, because he'll see this as a chance to play.

In my opinion aptasia is a problem at 20%. It can multiply like no tomorrow. The tinsy fragments of this anemones reproduce. If you notice when you stab alot of white stringy material floating in the tank....GET IT OUT. Out side of that there is a chance that it will divide into tiny frags all over.

The best way to remove them entirely is wash them off out of the tank. Or the kalkwasser mixture, as this does not have to be entirely injected. The reminant of the kalkwasser will be consumed by the aptasia and kill it.

I am not say that Nancy's or Colin's suggestion is wrong at all. Simply that I have had fights with the critters in my reef, and to leave chance that any of them are left in there is a mistake I had to realize I was making.

An octo in the tank would change the whole equation, and I would definatly reduce the chance of it stabbing itself while playing, by washing outside of the tank.


I'm an old hand at reefing... it's not the first time I've had to go on a rampage with aptasia. Generally, I keep a few peppermint shrimp and don't worry about them too much. In this case, the peppermint would surely become a snack, so that's out. I've had some success with the kalkwasser method, time to get out the syringe :smile:

I really had my heart set on a bimac, from what I've read, this seems like the ideal ceph pet. I believe that I'll try the bimac in this 29g tank, with the knowledge that I may very well have to upgrade the tank in a few months. I have several tanks, including a 120g reef... what's one more :smile:

Havn't heard any word on bristle worms, they've gotten fat eating the seahorse food in this tank. I kinda like bristles, they do a great job of eating leftover food, keeping the water quality up, but I'd hate to give my future octo heartburn from eating bristleworms!

I did find another thread that talked about macro algae with an octo, it appears that the calurpa should be fine. I'd imagine that the volume of macro growing will drop off when I change the lighting.

I'm picturing having a single piece of glass cut to fit over the entire top of the tank. Since there's no cords, airlines, etc. going into the tank, this ought to be ideal for keeping the critter in (perhaps with a bit of weight holding it down). That, and a couple of sponges over the inlet/outlet pipes, should be pretty secure.

Still waiting for info on the DSB... I'm a huge fan of DSB's, and this one's fairly mature, with a healthy population of critters. I'd hate to have to loose it.

I appreciate all the responses, and if I forgot to mention it, Nice site :smile:
Ooops, I think I gave the wrong impression about the effectiveness of using the boiling water to kill aptasia - I meant that it's about 80% effective on the first pass - then you go back and kill anyone left in a day or two. So it can be 100% effective.

If you have other tanks so you could handle it if your bimac got too large, then try the smaller tank.

I had bristle worms with my bimac, but when she laid eggs, she seemed to consider them a threat and killed some of them.

Bear in mind that any plant or featherduster or whatever will be seen as part of the landscape that your octo may rearrange, cover with large rocks, or whatever. They are strong and like to change their environment. A baby bimac will do this only on a small scale, but when it gets larger.....

DSB to come...

As for the tank size, you could still get a bimac, just hope that it doesn't grow too big.
The bristle worms can be left alone as octopus are messy eaters, the worms will certainly help.
Thanks :smile:

Thanks for all the replies, everyone...

Here's the plan, this weekend, I'm kalk-ing the aptasia, and dosing flatworm eXit while I'm at it, and securing everything. Going to pick up a sheet of plexiglass to cover the top, perhaps see if I can come up with a clever way of keeping it in place, rather than using duct tape... and covering my inlet/outlets with sponges (wire tied in place??). I'm also going to add a carbon charge to the sump, and give my skimmer, pumps, etc. a good cleaning.

I'm planning on leaving the DSB in place, unless someone convinces me otherwise...

Sounds like, other than tank size, my original plan was pretty sound :smile: I've got a line on a 40g breeder tank someone's selling fairly cheap... think this would give the little guy enough room?
Hi cmidkiff,

Don't use any wire for tying - use something like plastic fish line.

Also, it would be good if you had some sort of ventilation in you lid - mine, which came with the tank, has some ventilation holes that I've covered with netting secured with duck tape.

Re: Thanks :smile:

cmidkiff said:
I'm planning on leaving the DSB in place, unless someone convinces me otherwise...

Well............................. LOL

am i right in thinking that the DSB is in the refugium in a seperate tank? In that case then it will be fine and the colonies of worms and such will be a great benefit!

DSBs have a shelf life of not much more than a couple of years and since an octo doesn't live that long its a mute point.

A DSB ceratinly wouldn't work in a tank the octopus was in... okay in a sump or similar!

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