Heater

Recommendations? Sure we've got plenty. If you were to look at all the discussions we've had here on this forum over the years, almost every single one of them reaches the conclusion that heaters need to be less wattage than recommended by the manufacturers, like only a 100 W for a 75 gal. Some hobbyists choose to use two smaller heaters, like two 50-75 W heaters for a 75 gal tank. Yes, the heater stays ON longer thereby reducing the number of On-Off cycles but that has the positive benefit of extending the life of the heater.

The reasoning here is simple. Heaters most often malfunction by sticking in the ON position. Think about it. A 300 W heater will cook a 75 gal tank in no time.

If there is a temperature cut off device, usually employed by relatively expensive Controllers, like Neptune/Apex, Digital Aquatics/Reefkeeper, Ecotech/Reeflink, etc. the heater is turned OFF if it malfunctions, but even those devices sometimes malfunction because they require a functioning temperature probe to be in the water and require a mis-programmable, electronic device to work properly. In my opinion, daily checking of a thermometer is an important safety measure. (I like the flat stick-on thermometers because they are accurate enough and are hardly noticeable when placed in a bottom corner)

While we are on the subject, I might as well mention, many of us who have been in this hobby for a long while, including knowledgeable tank maintenance professionals, will set the heater at around 74-75 and may even disconnect the heater in the Summer. There are at least three reasons for this here at ~4300 feet above sea level:

1) Fish and coral do great at 75 degrees because cooler water holds more Oxygen, making it easier for them to breathe and because metabolism slows at cooler temperature, they don't need as much O2, breathing slower. The two benefits complement each other. In my personal experience, a reef tank can get down to slightly below 65 and still be okay as it warms up. The acceptable range for a reef aquarium at our elevation is 70-80 degrees. Over 80 degrees can lead to serious problems immediately and/or in the days that follow. 

1a) I believe that the recommendation above applies specifically to higher elevations where the air is thinner. At sea level, because of higher air pressure, the water can be 80 and hold more dissolved O2 than at high elevation.

2) If a problem develops in the tank, bad things happen slower at lower temperature so there is time for the hobbyist to notice the issue and fix it before the tank crashes

3) When the house heats up in the afternoon, when summer warmth causes home temperature to rise or if the heater sticks ON, at 75 the tank will have a buffer so that it takes more time to reach the critical temp of +80 degrees, again giving more time for the owner to discover the problem, fix the heater, turn on the home A/C and/or point a fan at the water surface to cool it down. 

3a) In our dry, low air pressure climate along the Wasatch Front, using a small fan to cool the water is extremely effective because of the same principle that makes a Swamp Cooler so effective, evaporative cooling.

Hope this helps. Differing points of view are welcomed.

Aloha,

Mark 

P.S.

Oh, and regarding brands, I've had the best luck with Jeager but that was before Ehiem bought them. These days any heater will work, though I avoid the cheapest ones. As soon as a heater malfunctions, I throw it out and buy a new one. This is one area where the "king of cheap" spares no expense.