Key Elements of Water Quality Part #2 - TEMPERATURE

The most effective temperature range for aquaponics to operate in is 68 to 75 F or 20 to 24 C.  That is not saying you can‘t operate one if the temperatures are not that.  I live in the tropics of Central America and we all know, it can get really hot.  It’s not always convenient to either cool the system or heat it.  It’s important that you build a system in such a way to naturally cool or heat first.  Then, if you have to, spend the money needed to do either.

Plants and fish are your most important considerations.  Decide what temp range you will be dealing with in your growing season.  You may be fortunate enough to be growing all year around versus having only a short season in colder climates.  Then you need to know the temp range for your plants and fish.  This will determine what you can grow and type of fish you can have in your system.  For example, you can have lettuce in cooler temps, but it will not do well in very hot climates.  The same goes for fish.  Tilapia, the temp range should be between 60-80 F and for Trout, it should be around 45-72 F.  There are multiple other fish to consider as well. 

But what if you are still having issues of being within the proper temperature range?  What if you have the right temps for the summer but you want to extend your growing season by starting earlier and extending it further into the fall?  Or you have scorching summer temps, but more moderate winter temps like in the tropics.  We now will discuss ways to either cool the water or heat it.

WHAT ARE WAYS TO COOL THE WATER?

Now, it’s time to build your system.  You have properly selected heat tolerant fish and plants, by doing so, you will only have to consider a minimal drop in water temps.  Before trying anything radical such as using ice (temporary fix only) or an inline cooler that can be very costly and doesn’t make sense for the hobby grower, you will want to build your system in such a way that will cool the water as best as possible.  

1.  The location of your system.  Build your system in the shade more so than in the sun.  This will give you a 5-degree heat reduction.  Obviously, you must consider the plants you will be utilizing.  How much sun do they need?

2.  Does the area have good natural airflow?  If not, can you build in such a way to install box fans?

3.  Consider the size of your system.  The more thermal mass, the less variation you will see over time in temperatures.  Remember, it takes longer for the larger system’s water to heat up, but it takes longer to cool them down.

4.  Bury your sump pit down in the ground.  On the average throughout the US, ground temperatures below 3 feet range around 45 to 50 degrees F.  Obviously, this would provide a cooling effect on the water in your system.

5.  Build a greenhouse with shade cloth over it.

6.  Paint the exteriors of your tanks and grow beds with a cooling color.  Don’t use something such as black.  We always use light blue paint for our systems.

7.  Insulate the exteriors of the tanks as well.  Some have reported a 2-degree drop in water temperatures by doing so.

8.  One trick I found and possibly an inexpensive way is to get a refrigerator.  Start by drilling two holes in the side, connect a hose to the pump in the sump pit, run it into the hole that you drilled, coil the hose up in the refrigerator, and then run it out into the fish tank.  This will cool the water and should be the last option.  The only problem you would have to consider is the head pressure on the pump.  It may require you to get a bigger pump with greater strength, thus require you to use more electric. 

As you can tell, there are easy ways to cool the water for your plants and fish.  Yes, I am sure there are some other considerations as well, but this will get you going in the right direction.  TO READ THE REST OF THIS ARTICLE, CLICK "READ MORE" IN LOWER RIGHT SECTION.

WHAT ARE WAYS TO HEAT THE WATER?

Building a greenhouse would be one of the foremost considerations when you are needing to heat your system water.  Since water in your system will adjust to the ambient temperatures, this would be a great way to go.  Also, it would extend your growing season out much more so.  If building a greenhouse is not an option, there are heaters available online that you can purchase.  You can find a variety of them by googling, “water heaters for aquaponics.”

What are ways to heat your greenhouse?

Let’s talk about some basics to consider as you approach this direction.

- Choose the right crops to grow for the season. Go for low-lying greens like kale, spinach, and mustard greens that can stand very cold temperatures.

- Invest in a good quality thermometer that can read max and min temperatures throughout the day.

- Only heat the areas necessary. Grouping plants together will help you save energy and cost.

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1.  Store Thermal Energy Using Thermal Mass 

Thermal mass materials are items that can absorb and store the solar heat energy and then release that heat in the evening time while temperatures are dropping.  This is one of the easiest ways to heat your greenhouse and most popular.

Here are some effective methods to collect thermal mass:

Idea 1: Use gravel or stone as a floor in your greenhouse.  It should be dark in color to absorb the heat as much as possible.  You can easily attain this gravel at your local nursery or gravel pit that sells to the public.  These rocks will release heat during the dark, cold hours all the while keeping your plants warm.

Idea 2:  Believe or not, water has a higher heat capacity than land or soil, try putting water or rain barrels around the interior of your greenhouse.  Especially, consider placing them on the southern portion of your greenhouse to where they will absorb the sunlight.  Place plants that are more dependent upon heat closer to these water barrels.

Idea 3:  Use cinder blocks or earthenware ceramic pots to further absorb solar heat.  If you have extra space around your system, they can be used to support planters on table-tops and benches.  They will release heat to the surrounding plants.

Note:  When using any of these ideas, you need to consider the color of the material.  In some cases, you might need to paint them black so they can absorb more heat.

2.  Build an Indoor Compost Pile

​I have seen this done in one aquaponics system to where they incorporated compost piles underneath the grow beds.  This is such a genius idea and one of the most sustainable techniques to keep your greenhouse warm.  It is so cost effective because it’s almost free to build.  You will not use any resources such as power or fuel.  The bacteria in the compost will be breaking down the organic material all the while generating heat.

3.  Insulation is Another Option

Not only would you want to cover the entire exterior in plastic sheeting, but you can cover your grow beds as well for added protection.  Plastic helps absorbs more heat without keeping the sunlight away from your crops.  Also, if you can get it at a great cost, bubble wrap would even be a better option.  The bigger the bubbles are the better.

4.  Make Sure You Properly Circulate the Air

You want the air moving within the greenhouse.  This will ensure that there are no pockets of cold air.  Make sure you add some ventilation, or you will end up growing plants in a humid, CO2 depleted environment. Mold, mildew, and fungus can become a threat.

5.  Use Heaters

There are so many types of heaters on the market, electric or fuel.  You need to ensure that this is a cost-effective option for you.  Then weigh out which would be the best as in monthly expense.  You can heat the air or water or both.

​Hope you enjoyed part 2 of "Water Quality."  Next week, we will be discussing how to ensure you have proper aeration for your fish, plants, and bacteria.  Oxygenating the water is a very important item that you can't afford to overlook.  Make sure you subscribe to our blog before leaving.  You don't want to miss our updates.

Thank you for stopping by.  I certainly hope you enjoyed this article.

Shawn Paul
MorningStar Aquaponics