Hi there
Firstly you need to stop apologising, we are all here to learn from & share
40g is a no bad size for a 1st Full Salt Tank
I will answer your questions in the order you asked/stated
Live Sand
Live Sand is just as the name suggests Sand that has been seeded with Microbale (sp) life, this will help your tank cycle and will feed any Inverts you get (ie Crabs, Starfish etc) (No where near as important as Live Rock)
Post Regarding Live Rock
Live Rock (IMO) is an absolute must for a Marine Tank, this the way of filtering your system have a read of
Post I replied to a couple of days ago, you can use a traditional Interal/External Filter to take care of the Bio-Filtration
But it is far easier, nicer, more natural to use that approprite amount of LR to keep you paremeters in sync, you will need some
form of rock for your fish to Hide, graze from/in and there is no better rock for a marine tank than FULLY CURED LIVE ROCK
IMO you will need about 20 - 25 kg of Live rock for this Tank
Skimmer I Recommend
A skimmer is another type of filtration it is an absoulte must (IMO) for a good tank, a skimmer removes uneaten food, and waste products from the tank (Proteins)
Now these proteins will always be in your tank, due to the fact that there is live in teh tank that neeeds to feed & poop, if left unattended these proteins will become toxic and kill all you livestock, so to stop this you must Protein Skim your tank and the instument to do this is a Tube/Box with tank water where air is constantly pumped throught it, on the top of this is a collection cup that collects the waste from your water (and boy is there waste, it is quite unbeleivable how much gunge actually comes out of a tank in a week)
New Skimmers use a pump to pump water throught the bottom of the Tube/Box and through a VENTURI Inlet, this causes millions of bubble in the water and basically the proteins are trapped on the bubble surface and as the foam/bubbles build it overspills and is deposited in to the cup, the cup will hold the Skimmate and isneeds to be cleaned regualarly, the skimmate should be either dark green (or black) and will smell real bad
Also with an overrated Skimmer you will be able to keep a slightly higher stocking level
Hydrometers & Refractometers
This is a plastic Swing arm device that will measure the specific gravity of your tank, and thus telling you the salt level (should be about 1.026)
IMO Hydrometers are Rubbish and I persoanlly only use a Refractometer, easier to use and a lot more accurate (more expensive thought)
Powerheads
These are simply look like Filters without any media, they are designed to move water around your tank, using the Berlin System (Live Rock, Skimmer) you will need to circulate your water over/around your Live Rock to feed the Benaficial Bacteria that colonise there, powerheads will do this for you.
IMO I would be looking to circulate the total tank volume about 20 -25 x (so around 4000 - 5000 lph) using I would suggest no leass than 3 powerheads (This will make sure that there are no dead spots in the tank (ie Rock that has little or no circulation over)
Heater: -
For a 40g tank I would use 2 x 150w heaters for a couple of reasons,
1 - I wouldnt trust just using one heater
2 - I will give a more even temp spread
Also the most important thing is Reading & Asking Questions
So Read & Ask Away
Del
Ps most of the Headings above a clickable and will show you a pic/description of what I mean
