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 Heater 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.