The temp in my tank may fluctuate from 78F during the day to 74F during the night. Is this o.k. for the fish or do I need to try and keep it more steady? I would think that in the wild their temperature fluctuates a few degrees from day to night.

You'll be okay, it is virtually impossible to keep a tank temperature exactly the same all the time as the room temperature will also have an effect on how warm the water is. Like you say, in the wild, water conditions change all the time, not only temperature, but also pH. The same thing happens in your home aquarium. Fish are okay with gradual changes in temperature, it's when it happened suddenly, that is when problems can arise

Thanks,
thats what I figured but wanted confirmation.

My tanks will vary a little but only but 2F. The heaters in my tanks are rated for larger tanks, this means they dont work so hard and so last longer. You are getting a 4F range. Are you heaters just enough for the tank, if so try adding a bigger or another heater to help stabalise the temperature

ive got two of those large eheim heaters rated for 1000l tank in my 120g tank and my temp doesnt fluctuate much either.

as delboy said if u over do it with the heating than its easier for the heater to keep the the temp stable.

Thanks everyone taht sounds like good advice. I will get a new heater for my tank. I believe the heater I have is just not strong enough.