My marine tank is soon to be up and running.However upon visiting the aquarium stores I go to I noticed some had heaters while others did not.Any thoughts on this as am not sure now if I should put one in or not.

Yes....unless your tank is in a place it never gets under 78f....I have two 300 watt heaters in my tank...and I live in Arizona....You want to maintain a constant temp between 78-81f.....

Thanks for info.Planning on putting fish in soon as tank just about cycling.Just need put heater in now.

What did you end up deciding to keep? Fish only, inverts, corals?

Not made final choice yet.I'll keep you all posted.

best heaters on the market is the Titanium heater