Not sure if this is the right place for this question.. but figured this is kind of a rookie question, well 2 really. First question is about heater placement- I currently have a 150w in my 40g placed horizontally under the intake near the bottom. Thought this would be sufficient, but now I'm thinking about placing a 2nd heater (also 150w) as a backup. It's pretty warm right now, but noticing the heater light is on a lot so maybe a 2nd would reduce some of the strain. My question is kinda silly, but how/ where would I put the 2nd heater? I liked the horizontal position, but I don't think I should stack them? Would they be ok vertically on either side of the tank, or is there a better option? My other question is about increasing oxygen, and whether or not it's necessary. Right now I'm only running an AC70, but it was suggested to me on another forum that I would need to add something for more oxygen. Is the filter alone enough, or should I add something? I have a spare AC30 and a Fluval powerhead (also rated for 30g) but I don't know if it's necessary or if they're too under powered? I'd like to keep things as uncluttered as possible, but I also want to start off right.