Water Culture systems and Deep Water Culture systems are nearly the same. The primary difference is the water depth. Recirculating Deep Water Cultures differ as they are similar to flood and drain systems, but in this case the water never drains.
The Hydroponic water culture system is a simple, inexpensive active hydroponic system. The plants are anchored in a floating platform, generally made of Styrofoam that drifts in a nutrient-filled reservoir. An air pump and stone system agitates the nutrient solution and furnishes oxygen to the plant roots.
It is the most popular hydroponic mode for fast growing lettuce and a few other green leafy vegetables and herbs, but does not work as well with larger or slower maturing plants.
Water Culture Equipment / Components
Container / Reservoir
A water tight container will suffice, aquariums are ideal. Should you choose to use an aquarium you’ll need to shield the water from light as algae growth is a chronic issue. Light also breaks down the nutrient solution. I have in the past used roofing felt as it was readily available to me, you can also use cardboard, poster board or any flexible material that can be fastened to the container to block light. Some people will spray paint the outside of the tank, which makes it difficult to peek at the root system progress or lack thereof.
Cups
Net pots are generally used however, should you choose to ‘cheap out’ small plastic tapered drinking cups, either plastic or Styrofoam will work just swell to hold the plants. The cups will need to be worked to allow for the flow of nutrient solution to the roots and also for expansion of the plant root system.
Platform
A slab of styrofoam at least 1.5 inches thick will work as a platform or raft into which the pots are set. The Styrofoam should fit loosely into your container/reservoir. It’s perfectly okay if it bobs about a bit.
Growing Media
A modest amount of growing medium to fill the plastic cups / pots is needed. A Perlite / Vermiculite blend works best but others such as clay pebbles will also do the trick. Avoid organic media for this system if possible. Sphagnum moss, peat, coco coir, although they have been successfully used problems with continuous water exposure in a water culture system outweigh the advantages.
Nutrient Solution / Fertilizer
A Suitable soluble nutrient solution geared for the particular crop you are growing.
Air Stone / Soaker Hose
A simple air pump and stone, such as that used in aquariums or a soaker hose is needed to oxygenate the nutrient solution and hence to root system. The roots in a water culture system are continuously submerged around the clock without oxygenation they would suffocate and rot away.
Aeration
Aeration, oxygenation is absolutely vital in a water culture hydroponic system.
Just like tidy bowl, the more tiny bubbles, the healthier a water culture systems is in relation to oxygenation. There should be enough bubbles to make the solution resemble a tempest in a tea pot.
A soaker hose is a tad more difficult to install and use but is a step from an air stone if properly implemented. Soaker hoses create smaller air bubbles which provide deeper oxygenation of the solution and helps in replacing dissolved oxygen that the plants have absorbed.
Other modes of oxygenating include Falling water and Recirculating Water Culture systems both of which work well, but are a tad more technical. Falling water systems are best for large or commercial water culture ventures that use large volumes of water. Falling water provides surface agitation of the water and hence oxygenation. The higher your waterfall, the bigger a splash it will make and the more dissolved oxygen will be forced into the reservoir.
Recirculating systems are similar to a flood and drain system, but the water in this case never drains. It is only recommended for more advanced growers and in my opinion is not worth the effort and expenditure when simpler and less problematic solutions are available.
Deep Water Culture
Deep Water Culture and Water culture hydroponic systems are basically variations of the same system. The primary difference being that in Deep Water Culture [DWC] the reservoir holds a larger volume of water / solution, and is deeper.
When the water depth approaches 9 to 10 inches it is referred to as a DWC system [Deep water Culture]. In most scenarios water this deep is not necessary and a waste of resources, however, larger plants with extensive root balls require more space and tend to be hungrier and thirstier than smaller ones, so hence a deeper reservoir is required.
One occasional issue with DWC systems is oxygenation of the root system, in basic water culture systems an air stone is generally used, in deep water culture you might want to consider using two, depending on the size of the system.