Posted on by Jason Gibson

Deep Water Culture - A-Grade Hydroponics


A lot of gardeners new to hydroponics often ask how long until they should change their nutrient solution.

There are many opinions on this topic so ill will keep it brief, realistically the whole concept of hydroponics is to grow without soil and save water?

Changing our nutrient solution on a weekly basis doesn’t seem very economical in regards to nutrient outgoings or promotion of water savings.

If your plants are healthy and your nutrient solution is being consumed evenly (pH & EC readings stay even) as the water level drops we should just be re-adding the lost volume.

So, if your starting reservoir capacity is 40L and each day your find your plants are consuming 4-6L of nutrient solution & water evenly, then we need to make up a fresh mix of the depleted nutrients & water to re-add to the reservoir.

Never fill your reservoir right up to the base of the net pot, roots need oxygen so fully submersing them in water will only suffocate the plant.

Ideally, you would have the solution about 3-4 inches below the base of the pot, this will allow excess oxygen & humidity to aid in fast root development.


Here I will share all of the items you will need to create your own deep water culture system using a common DWC design.

First things first, you will need these tools:

  • Drill
  • 4mm Drill bit
  • 140mm Hole saw


Next up is our required materials:

STEP 1 – Place Lid on tank securely, attach hole-saw plate to drill, start drilling your required number of pot holes. I’d recommend starting with just 1 per tank. 

STEP 2- Attach 4mm Drill bit to drill and drill two holes in one side of the tank under the lip approx. 10cm apart, Remove excess plastic dust and clean tank. 

STEP 3 – Thread desired length of 4mm airline through holes roughly towards the center of the tank then attach the air stones to the ends. 

STEP 4 – Attach the other ends of the airline to the outlets on the Air pump, DO NOT plug it in just yet.

STEP 5 – Fill up reservoir with required amount of water – for 52L tanks I recommend 35L and for 68L tanks I recommend 45L

STEP 6 – Add the required amount of nutrients & Root tonic to the water.

STEP 7 – Transplant seedling or cutting into 140mm mesh pot and cover over with the pre-washed Hydroclay stones (This will help root growth and also prevent light from entering the reservoir, which can cause many problems)

STEP 8 – Turn on Air Pump and turn dial up to around 75%

STEP 9 – Using the freshly mixed up solution, fill a jug with the mix and top feed the new cutting.

STEP 10 – Check pH and EC of nutrient solution to double check all of your numbers are correct and within range. 

Now you are good to go in your brand new deep water culture system!

Happy growing, please submit comments below if there are any questions I haven’t covered.

Deep Water Culture - A-Grade Hydroponics

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