I assume you mean 40 pounds of live rock and some live sand?
Some background...my setup, for comparison, is as follows:
55 gal tank
220 watts homebuilt Power Compact Fluorescent lighting (Aquarim Hobbyist Supply)
~55 pounds live rock (Harbor Aquatics)
~20 pounds live sand plus normal aragonite
Eheim 2026 canister filter
CPR Bak-pak protein skimmer
2 powerheads, either end of tank
I don't know about how much light coralline algae need...but I believe I've been told before that they don't need really strong lighting, and I do have it growing nicely in some of the darker crevices in my live rock (I have strong lighting for some corals.)
If you want lots of pretty corals, you need lots of quality light. You can, however, pick and choose carefully and have certain low-light corals with weaker lighting and smart placement in the tank...so keeping your light at a more sane level is not the sacrifice it sometimes is discussed as. And in general, octos prefer weaker light...if you want to see him out more in the day, it's more likely if your lights aren't as bright as mine are. :P If your tank comes with some built-in lighting, that may even be enough...otherwise, you prolly don't need more than 100 watts of fluorescent, maybe even a lot less. AH supply is a good resource for building your own lights, which is easier than you'd think, but for such low light needs you can probably find good cheap stuff off the shelf.
Lots of opinions on how to set up/filter a tank. I don't have a lot of critters...a few echinoderms (urchins and starfish), some corals, a tiny octo and that's about it. I don't know what the limits are of what my tank can hold, but since I intend to keep it an octo tank, I'll prolly never find out...no point it jamming it full of pretty fish if they're only octo-dinner!
I find my Eheim very nice and easy to use, it's a fancy filter. It provides the main mechanical filtration (just getting particles of various size out) plus water circulation and a bit of biofiltration (bacterial chomping of wastes.) My CPR bak-pak pulls waste directly out of the water before it becomes a problem...a GOOD protein skimmer is essential for an octo-tank, they are very sensitive to wastes and other bad stuff. The bak-pak provides my main "backup" biofiltration with its bio-bale chamber.
THe most critical part of my tank's setup, however, is the live rock. Excellent quality live rock, fully cured and just covered with critters of all sorts. All the bacteria living in the rock do wonders for my tank...since I first cycled it, I've never had detectable levels of any waste products. Good live rock like mine will gobble it up that fast (unless you have a lot of animals in the tank making a lot of waste...octos are known for that!
) This also means I do less frequent water changes...but recently I've stepped mine up anyway, and I'd recommend the same...some waste components in the water aren't entirely detectable but are most definitely there, and need to be taken out anyway.
THe live sand I added probably helped me accelerate the cycling of the tank. I first set up just the live/aragonite sand mix (about 20 pounds of each) with water and the filtration equipment and just ran it for almost a week. Then I added the live rock and ran it some more. Cycled very quickly this way. Then I added critters very cautiously, one by one, and watched my chemistry very closely.
So...all this wordiness is really just to say "here's what I did and what I think you can do." THere are other ways to do this. If I was building my tank today, I'd use all this equipment but put it in a sump...there are advantages to having one of those. If you go my way, an Eheim isn't necessary...any decent canister filter will do. The Magnum 350, price/performance-wise, prolly can't be beat...all I've ever heard is that it's a great filter, durable, and cheap. You maybe could even use the smaller, cheaper hang-on-tank 250, though we're constantly told "buy more filter than you need" for lots of reasons. Likewise, there are other good (indeed, better) skimmers out there besides the one I'm using.
Uh...I didn't mention tapwater prefiltration 'cause you didn't ask...that's a whole other category...you need good filtration there and it isn't cheap, but there may be a cheap way out that MAY work for you. Ask if you want to know more, I've blabbered on here for way too long and other people more experienced than me will have better advice for you anyway! :P
rusty
trying to setup an octopus tank, I have a 40gal tank can anyone give me a spicific list of equipment i will need. I plan on setting my tank up with 40 lbs of live and some live sand. It appear you don't need very strong lights, wont this affect the coriline alge growth on the rock, can you add calcium with an octo in the tank?
