It’s a very overlooked issue of hydroponics that oxygen content in water is so important. Using a water chillier for a hydroponics nutrient solution can be highly beneficial for the rapid and healthy growth of plants because lower temperatures means higher oxygen content and larger yields. For example, a hydroponics system in most cases uses a circulating pump to circulate the water solution around the system whether DWC, NFT or flood and drain this adds heat to the water. Add to that the ambient temperature of the surroundings and indoor lights, water temperature in a indoor growing environment can rise to levels where oxygen content in the water can be extremely poor. When grown in soil, plants roots are always kept at a steady temperature naturally, but when grown in water the heat from the surrounding heat sources conduct into the water. Water is a good conductor for heat hence why it is used as a coolant in automotive, industrial and manufacturing processes.
Plants Roots Require Good Oxygen Levels:
Plants grown in systems using Flood and Drain, DWC, Centralised bucket, recycling systems, NFT and Aeroponics require a good mg/L oxygen content flow and water can hold more oxygen at lower temperatures. In most hydroponics systems the ideal water temperature needs to be between 18DegC and 24DegC, pathogens like warm water and can soon take hold in warm water conditions making root systems brown and redundant. The temperature set point really depends on the system being used, see recommendations below. When the water is cooled to an acceptable temperature the plant roots gets all the right signals and can flourish with a good level of oxygen in the water. A good example regards temperature and oxygen content in water, at 30DegC fresh water can hold up to 6 mg/L while at 20DegC fresh water can hold up to 9mg/L, almost 50% more oxygen content. That means a whole lot more yield potential.
Our Recommended Operating Temperatures By System:
DWC: 22 to 24 DegC
Aero: 18 to 24 DegC
Centralised Bucket: 22 to 24 DegC
NFT: 18 to 24 DegC
Flood And Drain: 22 to 24 DegC
Water Chiller Versus Air Conditioning:
In most indoor grow areas the environment can get hot due to lights, pumps and other heat loads. Most growers use a air conditioning unit to try and combat the heat directly at the source. This can cause problems with humidity as a result of direct cooling. This process can take a lot of moister out of the area and dry the plants out. Plants thrive in warm humid environments and can take high temperatures and transpire very effectively as long as the roots are cool. When a water chiller is used the ambient temperature and humidity can be significantly higher than the water temperature and the oxygen levels in the water will not be affected by the ambient room temperature.
Important Options When Buying A Hydroponics Water Chiller:
It is very important to buy a hydroponics water chiller with a titanium heat exchanger. If your chiller has not got a titanium heat exchanger than contamination between the metal can spoil the nutrient solution. Because many hydroponics nutrient solutions have a high acid or alkaline content this can corrode cheap base metals to the extent that metal peroration and contamination of the water becomes a issue to your background water levels.
Sizing Up Your Hydroponics Water Chiller:
It is reasonably straight forward to size up your water chiller for hydroponics use. All chillers have a rating, for example 100 watts output, this means the unit will cool approximately 100 Litres of water. In cooling terms 1 watt of cooling will do 1 litre of water. If you are using a DWC system with 5 x 15 litre buckets and have a buffer tank of say 40 litres you will require:
5 x 15 for the buckets = 75 Litres
Plus the buffer tank = 40 Litres
Total Litres = 115 Litres
Add 10% for heat losses = 11.5
Total Required = 126.5 Litres
Therefore you will require a chiller with a rating of +126 litre cooling capacity.
This means your hydroponics system requires a hydroponics chiller unit as close as possible to that figure but never below this mark.
Here is an examples:
Pro’s and Cons of a hydroponics water chiller:
A hydroponics water chiller combats heat where it matters
Improves oxygen levels in the water
Repels pathogens in the root mass of plants
Ideal for NFT, F&D, DWC and Aeroponics
Many hydroponics water chillers have a air filter which acts as a air cleaner
A water chiller does not dry out the room like air conditioning though they can be used together
The heat load from the water chiller has to be extracted from the room
Noise levels and vibration from cheap water chillers can be annoying
Cheap water chillers don’t have a titanium heat exchanger
Source: Orion Air, (http://www.orionair.co.uk)