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R/O Water

Aug 6, 2003
I probably should have asked this before but is R/O water neccesary? I've had my octo in there for four days and he seems to be doing fine. He ate the first day, comes out quite a bit to play with marbles and climbs on the walls then jumps off. Just wanted to know if I should add some now. Thanks in advance.


Staff member
Nov 20, 2002
Yes, you should be using R/O or RO/DI water. It's the safest thing to do, and octopuses are very sensitive to copper or other metals in the water.

I've found that local water often varies in the amount of copper and other harmful elements - in other words, you can't depend on it.

What sort of water are you using now?



Dec 2, 2002
Using tap water is a roll of the dice. I set up my first octopus tank with tap water and raised a bimac just fine. Later, I hatched out and reared several O mercatoris and kept a pet vulgaris. Just three miles down the road, and set up my tanks with tap water again. The first octopus lived a few months, the second a few hours. I tried adjusting the filter. I got a shipment of cuttles from the NRCC and THEY died. I tried other things. I tested for everything you can test for- ph nitro compounds, heavy metals, copper....it all came up nil. I added a toxin sponge compound to the filter and changed out the all-activated carbon canister filter. Instead of sacrificing another cephalopod to Jimbo's Cephalopod Gas Chamber, I added cheaper, more mundane creatures in cluding some starfish that IMHO are way more delicate than cephalopods....and they thrived. Satisified with this fix, I ordered three baby bimacs from the now-defunct cephsource. They all died inside of a week.

Then I bought and installed a cheap kent marine RO unit, and generated the water necessary to do a total tank teardown. After going through all the amazing hassle of completely redoing a tank with all fresh mixed water and re-cycling it, I ordered another cephalopod....and watched it carefully for day after day after day after day.....

It's been fine since. With basic RO units going for less than a hundred bucks (http://www.drsfostersmith.com/product/prod_Display.cfm?siteid=6&pCatId=4467), save yourself TONS of aggravation.

Rock on, Jimbo
Aug 6, 2003
Thanks, I got one for $125 at the LFS. I've got yet another question, how long does it take for bimacs to mature? ( I've got a 130 gallon from one of my mom's friends but I have to cycle it, add live rock, etc. etc...) And are there any signs of when they're about to die?

My octo is still doing well, but i've spoiled him and now won't take frozen food, he only wants hermit crabs :roll: . I'll get some pictures posted when I can get a good shot of him.

Thanks again.

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