Ambient Cooling
Lesson 1
Essential Hatchery Components
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Temperature Control
Kelp should be cultured at a temperature of 50°F (10°C). There are two different ways that the seawater in the tanks can be temperature-controlled: either through plumbing a pump to circulate your water to a chiller or cooling the room to the temperature you want your tanks to operate at. As with most decisions, there are pros and cons for each option.
Two ways to chill your tanks:
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Chillers
Ambient cooling
It’s possible to keep the water in your tanks at the correct temperature by keeping the room in which they’re stored at the desired temperature. You can accomplish this by using an air conditioner, a heat pump, or another temperature control system that allows you to maintain the ambient temperature of the room. In cooler climates where outside air temperatures are commonly around 50°F during the hatchery season, this type of cooling might make a lot of sense.
The advantages of chilling the whole room is that it reduces the equipment costs and the hassle of plumbing pumps and chillers. The downside is that it can be difficult to find temperature-controlled spaces, and there are high upfront costs to build one yourself. For large-scale hatchery operations, an ambient cooling system makes a lot of sense.
Chillers
Chillers are small refrigeration devices that are plumbed to the tank system to cool the water that circulates through them. They allow you to control water temperatures at the tank level. This can be helpful if you’re growing multiple seaweed species that require different temperatures. For 40 gallons of water, GreenWave uses Coralife ⅙ horsepower (HP) chillers. The more water you need to chill, the higher the horsepower you’ll require. Be sure to review the chiller’s manual to see what will work best for your tank system.
A pro of using chillers is that they’re modular. For a small hatchery, they can be a cost-effective way of cooling your tanks, rather than investing in an expensive temperature-controlled room. They can typically be purchased from the same places you can find fish tanks, such as Petco, Amazon, or specialty stores like Aquacave. Start looking early, as sometimes they can be hard to find.
The cons of using chillers are that they require several additional components, such as pumps and tubing, and that they take a fair bit of effort to install and maintain. The plumbing needed to support your chillers can also make your hatchery design a little more complicated. You’ll need to make sure the water can recirculate back to the tanks and that there is space on your shelving for all the different components. We recommend that you sketch out a design and double-check your dimensions before making any purchases.
Chillers also emit a lot of heat. This raises the ambient temperature of your room, which can lead to the need for some kind of air-conditioning (AC) system to offset heat output. Without an AC system, the chillers may overheat and not properly chill your water. This is the main reason why some hatcheries decide to go with the more expensive chilled room method. One strategy to avoid this excess heat is to move your chillers to a different room, but that will require stronger pumps to circulate the water in your tanks.
Pumps
If you are using chillers, you will need a pump to circulate the water between your tank and the chiller. The power of the pump you choose depends on the difference in height between the surface of the water and the inlet of your chiller. This is called the head height. The higher the head, the more power will be needed to push the water from the tank up to the chiller. Refer to the pump’s user manual for a flow chart with power level recommendations for your head height. You can install a flow gauge and ball valve after installing your pump to adjust the flow rate if the pump is too powerful.
