• Looking to buy a cephalopod? Check out Tomh's Cephs Forum, and this post in particular shares important info about our policies as it relates to responsible ceph-keeping.

I'm sure I can guess the answer, but...


Nov 18, 2003
Heyyy I'm new here, everybody give me a big hand!

Truly, I wish this site had been here a few years back when I had my bimac. It was my first ceph, practically my first saltwater tank, and octo information was hard to come by - thus, I probably wasn't as prepared as I should have been.

Anyway, on to my question: How absolutely essential is an RO/DI filter? Has anyone successfully kept cephs without one? How can I find out what's in my tapwater, and how do I know if it's gentle enough for an octopus?

I'm planning to get another octopus in the semi-distant future, and to do it right this time. Probably another bimac, but we'll see. Which reminds me, is there a list somewhere on the site of commonly sold ceph species, preferably with descriptions and care information?

Thanks in advance, it's great to have found a place with such knowledgeable people.
Hello Me,

Welcome to TONMO.com!

Most of us use RO/DI water, but you don't have to buy a filter, since the water's available from some grocery stores and other places. Your local LFSs should sell it, too.

I think some people use just RO water, but many feel that RO/DI is necessary.

All the best,
I would certainly advise its use... I studied water quality in the UK and can say that its really not ideal.

Your local authoity should be able to provide you with a water analysis... some pharmacys will also do it apparantly
When we started up our saltwater tanks, we went to one of those water dispensing windmills in the parking lot of our local grocery store & bought water. It has all the info about the filtration on the side of it. Most grocery stores have a water dispensing machine out front or in the parking lot We filled up our 5 gallon buckets and 5 gal. collapsible camping water bags. BTW, I would highly recommend these things, they pack flat & work great!


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