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Bought my Octo Tank

Feb 19, 2003
After researching octopus all over the internet for almost a full year, I feel ready to take the pluge. I bought a used tank last week that meets all of the requirements. And this whole set-up cost only $300

37 gallon glass oceanic aquarium
Wet-dry Filter
Power Compact Lighting
Stand, Lid and Canopy

Unfortunately, this set up did not come with a skimmer. I think this tank will have a single bimac. I have about $500 left to spend, and the octo itself will coast $40, and it will be aquarium bred and young when I buy it. I know live rock and live sand I'm going to have to get, but how much of each? I've seen figures suggesting 1 pound live rock per gallon and 4-6 inches of live sand. I also remember reading that octopuses prefer rocky enviroments to sand? Should I cover my sand with large smooth gravel? It seems that the denitrification that anarobic enviroments provides is too valueable to loose.

I know I don't have a skimmer, but I figure I could get one with my empolyee discount at my LFS. However, I was wondering if a routinely changed poly filter would also be a good idea in an octo tank. It would be much easier on the wallet then a skimmer, and it says it removes nitrate, excess ammonia and heavy metals, all of which are very deadly for an octo.

How important is RO/DI water? I know it's essential for water to be pure, and my local water is pretty bad, we have chloromines. I suppose I could just buy some for now and get a unit at a later date.

I read on one site that the reason most octos suffer in home aquaria is because of low dissolved oxygen levels, and the major reason why nitrous compounds hurt octopus is because occupy too much space for the oxygen to dissolve in solution. Wouldn't a large wet/dry resolve this situation?

Any more advice? I'm open to all sorts of ideas.

With 500 to spend I would highly recommend getting a larger tank. The 37 will work to start, but a full grown bimac really needs a 55.

A skimmer is a must. You want to remove protein, and a poly won't do that. A poly wouldbe a benefitial ADDITION to you system, but not a replacement for anything. What size wet/dry did you get for a 37 gallon - a slimline 60 mebbe?

Use silver sand or fine sand. The coral sand can cut an octo. I don't believe you need that depth though.

RO/DI or distilled water is a must!! Don't use spring water!

And yes more filtration is always better for an octo tank.

Hope all of this helps. :biggrin2:
Hi and welcome to Tonmo.com :welcome:

Most of us have wet/dry filters and protein skimmers. You're going to need that skimmer - I put in a polyfilter along with my other filters and it did seem to do some good, but would be no substitute for the skimmer.

Most of us have powerhead pumps, in addition to the other equipment.

Please click on the Ceph Care button above and this will take you to our ceph care articles. Have a look at the Equipment List and also the Checklist for a lot of valuable information.

Your tank is on the small side - we originally said a minimum of 30 gallons for a bimac (and some people were successful with this size tank), but others needed at least a 50 gallon tank.

A lot of us use RO/DI water, others use RO water - I don't think this will be an option for you.

Hope that's a good start for you.

55 Gallons, for a single octo with a arm to arm length of one foot, with only 20% of that being mantle length? I already have 5 tanks, and I'm frankly more afraid of the floor caving in then anything else. How big did the bimacs get that needed that kind of room? I read all of the articles and I look and feel golden on all counts, but on this forum and in the articles, people say that the minimium tank is a 30 gallon. What happened to add the extra size? Some bimacs grew that much bigger all of a sudden? My bimac is coming Aquacultured and bred from the University of Texas, and they said a 30 gallon would be plenty of room for one of their bimacs. Plus I want to put the tank facing my bed, and a fifty five would be something to trip over every morning. Any ideas on what made these bimacs in particular grow to be that large?
It is not just their size, but the anmount of waste an octo can make. A 30 has worked, but many found out quick that their bimac out grew a 30 later on. Thats why I said it was fine to start, but felt like you should be warned.

Feeding habits do have alot to do with their size.

Some bimacs arm length get longer than 12".

Can someone please update the required tank size for a bimac on this forum?? :bugout:
also depending on the temp, and location of your tank. You will need a chiller for a bimac, often moreso than a heater. If I remember correctly, and if you live in TX, it gets hot in the summer there. And then again cold in winter in North Texas. Bimacs are a cold water octo. :biggrin2:

Do you have contacts at UT? are they keeping their octos with that deep of a sand bed, and not in cooler water temps? :bonk:
Actually, I live in CT, but the manager at the LFS where I work knows everybody when it comes to fish and aquaria. He has his contacts there. He tells me what he knows and what they tell him. The deep sand bed was my idea, as anarobic areas seem to be very benifical, and there are more of them with fine sand and depth. In the summer though it does get pretty hot. I want to keep the temp between 60 and 70, and for that I need a heater in the winter, but in the summer I figure I'm going to use ice cubes made from distilled water to get it down. Chillers alone are +300 and I need alot to spend on live rock and food.
I can get a bigger tank in the future, but I want to give the one I just bought a shot first. I'll try this out, but if wastes are too tough to manage or he just plain outgrows it I can certainly get a bigger tank, I figure a 55 gallon, but the one that's 36x18x18, not the 4ft one. I just really like this tank I got and I figure I can successfully work with it for at least a few months or so.
For a while that tank will work, and there are ways to keep their size down by feeding every other day. You may have complete success with a 37! I will hope it works. :biggrin2:

I live in Florida so I have a situation with heat :P , but as long as my ac keeps working I am fine.
Just a note on the U.of Texas comment about the 30 gallon tank. I recently visited those bimacs at the NRCC, and saw how they were being kept. The older ones that are being kept individually have no live rock or much of anything in the tank except some gravel and maybe a flowerpot for the bimac to live in. Waste is no problem because of how water is handled for the whole system. This is more like a lab environment and if kept like this, 30 gallons probably would be OK.

Also, about bimac size. The last generation of bimacs grew to various sizes. There were several large ones, including my Ollie, In Cephalopods, a World Guide, bimac size is given as "body to 12 cm, arms to 35 cm". That's about a 5 inch mantle, and 14 inch arms. Ollie was much bigger than that, with a 7 or 8 inch mantle, and her arms could reach well over 20 inches each. At the time of her death, she weighed 3 lbs 2 oz, no small size.

...but on this forum and in the articles, people say that the minimium tank is a 30 gallon. What happened to add the extra size?

Experience I'd say... it wasn't that long ago that there was nothing information- wise available for budding ceph keepers and 30 gal was plenty, but as nancy has said; as time has went on and husbandry has improved some of them are groing bigger and living longer, a testimony to the many people in this site who aim to keep cephs as best they can.

as the saying goes... bigger is better

bimacs actually live on mud flats in the wild so fine sand is better, but as nick said that is too deep, you only need 1" maximum... anaerobic conditions CANNOT be maintained in a tank with an octopus suitable for making nitrate into nitrogen.

hope this helps

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