Thank you very much for your advice. The final plan for my tank seems to be shaping up, but I have a few l last major questions. 1) Although I asked in a few of my last posts about my filtration, I have encountered some difficulty in deciding on the best equipment. Several choices are available and I would appreciate any advice that would make this decision any easier. As mentioned earlier, I plan to keep a 40-gallon tank with live sand, but NOT live rock (cost). The first option in a H.O.T (hang-on-tank) Magnum Pro System ($54.99). It contains a hang-on-tank canister filter AND Bio-Wheel Pro 30 spray bar for biological filtration. It is rated for 250 gph. The second choice is similar to the first, but is the Magnum 350 Pro System. It has a regular stand up canister filter AND a Bio-Wheel Pro 60 (two Bio-Wheel 30s) for biological filtration. It is rated for 350 gph. After reading other posts on this site, I have considered a more expensive third choice. For mechanical/chemical filtration I have considered a Fluval MSF 104 Filter for 125 gph. Since I have read that canister filters are poor choices for biological filtration, a separate supplementary biological filter seemed necessary. For biological filtration, since I'm not using live rock, a Fluidized Bed Filter (up to 300 gallons) ($53.99) was a possibility. The third choice is the most expensive and the least favorable. Since I'm not using live rock, but I am using aragonite sand, should I use a supplementary biological filtration? If so, can a spray be used? (NOTE: all of these filters can be found on doctorsfostersmith.com) 2) What brand and sort of air pumps would be good choices to provide oxygenation? 3) Since bimaculoides was mentioned to be a good species for a 40 gallon tank, will supplementary chilling/heating be necessary? Being in Chicago, IL, the temperature varies: 20s in the winter and 90s in the summer. 4) After looking in a fish catalog, a cheap tap water filter ($29.99) seemed appealing. However, it only uses carbon and ion-exchange resin. Can a tap water filter of this type be used, or will I have to invest in an expensive RO unit? I thank anyone who has offered advice in the past, and anybody who will. Without this message-board, the raising of the octopus would be difficult, if not impossible for me.