Fist the lighting, how long should I have my lights on? It's a 48 inch double bulb strip with one grow light, and one to make the fish look good
Regardless of lighting, lights should be kept on no more than 12 hours. 10-12 is the norm, but if algae starts to gain a foothold, most people will dial them back to 8 hours, give or take.
Also I have 4 potted plants all different types of swards, and am planning on adding 3 or 4 more plants. Will I need C02?
With the normal two bulb hood(And by the sounds of it, one of your bulbs is actinic, which looks nice but doesn't do much for plants), you don't have much light, so CO2 won't help a whole lot, IMHO. You certainly don't need it, but it won't hurt either. with good lighting, CO2 makes a
huge difference to plants, and can also keep certain forms of algae(Namely Black Brush Algea, BBA) at bay.
I'm lost on the C02 things what does it do, do I need it, and what would it cost me?
CO2 injection injects carbon dioxide gas (CO2) into your water. Plants need carbon to grow, which they will take from the CO2. Without injection, levels are usually less than 10 PPM; The optimum for plants is 20-30(at least the closes to optimum without harming fish).
Once again, no one 'needs' CO2, but it makes a very noticable difference. The only down side to it, is that it lowers the PH of your water, and if your KH(Carbonate hardness; your water's ability to buffer PH) is low, PH swings can become a problem.
As for cost, that depends.. You can spend well over a hundred dollars on a tank, regulator and other equipment for an elaborate set up, or you can make your own DIY CO2 reactor, from a 2L bottle, sugar, yeast, and some airline tubing for around $10.
Here is an excellent thread on CO2, and how to make it yourself:
DephC's CO2 sticky
As an aside, I use the DIY method myself, on my 29 gallon. I have three 2L bottles.
do need to get special water from the fish store to do changes? They told me they have water I could buy that would be better for my tank. Also how much water should I change and how often?
Hahaha... that is funny. You definately DO NOT need 'special' water; all you need is water conditioner, which removes chlorine/chloramine from your tapwater. That store is trying make more money off of you; if it were me, I'd find a new store. If toey are unscroupulous enough to try to sell you water, God only knows what they'll try to pull next.
As for the water changes, that all depends on your bioload(Number/size of fish), and the type of fish stocked(Some fish are very fussy about water quality, and require more frequent changes). The general rule to go by, for a light-to-average stocked aquarium, is 10% once per week.
