Temperature and Reef Aquaria

My tank temperature is too high! How do I keep heat from building up? How can I reduce heat in my tank? What other side effects of heat are there, and what can I do about them? These are the questions that plague reefkeepers' minds.

Although the first two questions, keeping heat from building up, and reducing heat in the tank, may seem the same, they divide the issues into proactive treatments, and reactive treatments. As with most things, being proactive is often cheaper, less time consuming, and better in the long run, but does nothing to solve immediate short term problems.

First, though, I would like to cover a couple "ideas", that persistently plague the rec.aquaria groups, and have some form of flaw:

• Dorm-style refrigerator converted into chiller: any contraption like this isn't going to work, as it is very underpowered and inefficient.
  
• Cool the room/house: Not a likely solution. There are two exceptions: some people have fishrooms (having been designed solely for the purpose of keeping tanks) and this you could cool using a properly sized industrial style air conditioner; or if you have an air conditioner immediately above the tank such that the cold air blows at the tank, you may cut down a couple degrees. Why it generally will not work: the air conditioner would have to cool the entire room (unless it's sealed, a room wont get much cooler than adjacent rooms)/house to a temperature below that of the tanks (which are about 75deg F)... your air conditioner will run constantly and you will have enormous electricity bills.
  

REACTIVE TREATMENTS:
Since people are most often looking to solve an immediate problem, we'll start with reducing heat in the tank. You'll have to remove heat from the tank and the there are only a couple ways to do that:

• Drawing Heat Out of the Water
  
  • Add a chiller. Although expensive, there are good reasons to do this: the price for a chiller, in the long run, is less then a dead tank of livestock! Unfortunately, people don't believe this could be the result, until it happens to them. Side effects: cost of chiller, cost of electricity to run chiller, cost and heat of powerheads to apply required flow over chiller coils (see Heat Revenge), and heat put out by chiller into the room. See the Chiller Sizing and Use article coming soon.
    
  • Add cold objects to/by tank. Do NOT add cold water/ice to tank directly, as this will certainly make a mess of things like pH, salinity, hardness, etc. Take either CLEAN zip lock bags or containers of water, freeze them and place them into the tank. One and two liter beverage bottles are excellent for this. Side effects: freezing temperatures may cause some cold pockets and could cause some livestock stress. Some thoughts:
    
    • Place the item in the sump instead of the tank, this keeps it away from lights and livestock and allows temperature to stabilize before it gets returned to the tank.
      
    • Aim powerheads at ice bag or container to reduce chance of cold pockets developing. This also helps the ice melt quickly (see Heat Revenge).
      
    • Be prepared to replace the ice containers A LOT! I would suggest having two or three sets of containers, one in the tank, and the others freezing.
      
• Evaporative Cooling
  Evaporative cooling could potentially cool your tank a couple to a few degrees. I think of evaporative cooling as more of a proactive treatment for not letting your tank get too hot, but use it as necessary. It is easy to implement, reasonably cheap, and has only one side effect: you have to add more make-up water more often - you may be surprised how much water will evaporate. This could potentially be slightly expensive depending on how you acquire your make-up water (if you're not purifying your water, you'd better!). And make sure not to over dose kalkwasser. You can increase evaporation either of the following ways:
  
  • Aim a fan at the water surface.
    
  • Increase surface agitation via the use of airstones and powerheads (see Heat Revenge).
    
• Do water changes, replacing the warm water with cooler water
  Although a potentially expensive and annoying process, this will certainly cool the tank. big changes in temperature necessitate large water changes and/or drastic difference in makeup water temperature. There are a number of side effects: cost of purified water, salt, and potential livestock stress arising from changing the water. A couple thoughts:
  
  • Be careful not to change the temperature too quickly.
    
  • Make sure you start with purified water.
    
  • Add water back to tank slowly, especially when replacement water is cold.
    

PROACTIVE TREATMENTS: Now, to avoid all that fire-fighting, scampering around and generally driving yourself crazy, let's take a look at ways of keeping heat from building up.

• Increase evaporation
  
• Decrease ambient room heat
  
• Decrease heat generated within tank, hood and sump
  

Given these basics, you've probably come up with a few ideas of your own, but we'll take a look at some methods:

• Evaporative cooling
  see above.
  
• Decrease Ambient Room Heat
  
  • Keep tank out of direct sunlight! This will also help algae problems if you have any.
    
  • If you haven't yet set up your tank or will entertain the possibility of moving it - find a cool location, away from other heat sources, especially out of sunny rooms. Basements are an excellent choice here.
    
  • Keep room temp to a reasonable temperature by using a room air conditioner.
    
  • Some people have the option of putting their sump in the basement (and pumping the water back up to ground floor) because they are often much cooler than the main floor. A large sump in a case like this can effectively reduce the effect of warm room temperatures, hot lights, etc.
    
  • Larger tanks have slower increases in temperature and aren't affected as much by hot lights, pump heat, etc. OTOH, they are harder to cool once hot.
    
  • Make sure you're not fighting against an incorrectly set heater!!
    
  • Insulation: especially useful for highly chilled tanks in warm, humid environments. Apply sheets of Styrofoam over any glass you'd don't mind being blocked out. This, of course, can be used to keep heat in when tanks are located in cold rooms.
• Decrease heat generated within tank, hood and sump
  
  • Use a fan in your hood to cool off and remove heat from around lights.
    
  • Reduce submersible power heads and pumps to an acceptable minimum.
    
  • Light ballasts should not be kept in the hood and should be removed to some place where their heat won't affect the tank. (This unthinking author originally decided he would place them out of sight under the sump, but those tar ballasts really cook!)
    
  • Consider temporarily decreasing duration of lighting or amount of lighting.
    

IN CONCLUSION:
Using these treatments, in whatever combination seems appropriate, will help alleviate your tank's heat problem.
Finally, if the temperature in your tank is getting kind of high, (I would worry when it's constantly approaching 85 deg. F) ensure oxygen saturation by increasing water surface agitation, keep the tank extra clean, cut back to a minimum acceptable level of feeding, try to limit any other environmental stress like introducing new organisms, etc.

Heat Revenge:
Any attempt to cool the tank, which involves adding a powerhead or any other type of submersible pump is going to add some heat to the tank. Hopefully, the heat added is not more than the heat removed by the cooling method!

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Written for RTO Features by Todd Zebert. Copyright 1996.