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DIY Hydroponics - How to Use a Flood and Drain Hydroponics System


Planting out your Flood and Drain SystemIn this section we are going to learn how to use our home made flood and drain hydroponics system that we constructed on the Building a Flood and Drain Hydroponics System page. This easy do it yourself flood and drain system was a snap to construct and it will be just as easy to use. The methods described here can be applied to just about any flood and drain hydroponics system. Flood and drain hydroponics is sometimes referred to as ebb and flow hydroponics and if you encounter a reference to ebb and flow hydroponics rest assured that we are talking about the exact same thing.

On the Building a Flood and Drain Hydroponics System page we finished our DIY hydroponics system by filling it with hydroclay and cycling water through it to check that everything was workng as it should. It should be pointed out that filling the growbed entirely with hydroclay is just one option, you can get appropriately sized pots and fill those with growing medium instead and place them inside the growbed where they will work just as well but need less growing medium. You are not even limited to hydroclay with this sytem, you can use rockwool, perlite, peat moss and many other types of growing medium but you must adjust the period that the system runs between flood cycles to accommodate the water retaining properties of the medium you are using or your results may not be as good as they could be.

Hydroclay was selected for this grow bed as it was intended that the hydroponics system would share a timer with an aquaponics sytem which floods for 15 minutes every hour starting at 5am and last flooding at 9pm. The rapidly draining hydroclay is ideal for this watering regime. If you were to use vermiculite you might only flood the system twice or three times a day to reflect vermiculites higher water retention and slower draining. The ideal timing of your flooding and draining cycles is to a degree a question of experimentation to suit your environment. As a general guide the growing medium should never be allowed to dry right out.

Planting out or Potting Up your Seedlings

Now we have a hydroponics system the next thing we need is, of course, some seedlings to plant. For our example here we are using silverbeet, cucumber and zuchinni seedlings that have been germinated in rockwool cubes by the same methods described in Starting Seedlings for Hydroponics. If your eager or cant be bothered starting seedlings another option is to go to a nursery and buy some seedlings instead. If you choose to buy them when selecting your punnet of seedlings care should be taken that you dont get any bonus extras in the form of insect pests, gently inspect the seedlings particularly the undersides of the leaves and ensure you are not getting more than you are paying for.

If you elect to use pots instead of simply filling the grow bed with growing medium then potting your seedlings up using the same method described on Using Top Feed Hydroponics is just fine. Pot them up, place them in the grow bed and you are ready to go. Its that easy. The only thing you need to take care about is that your chosen pot is taller than the high water mark of the grow bed. You can take spacers out of the outlet in our system if it is necessary or simply use taller pots.

Rockwool cube is level with the top of the mediumIf you are not using pots and planting out directly into the grow bed it will take you all of five minutes to fill your grow tub. To plant seedlings that have been started in rockwool cubes divide them if necessary with a sharp knife and scoop a hole in the growing medium deep enough so that the top of the cube will be level with the top of the medium. Dont bury them but keep the top of the cube pretty level with the top of the medium. Fill the sides of the hole with medium and the plant is ready to go.

If you have chosen to use a punnet of seedlings bought from a nursery planting is just a little different. Start by dividing the seedlings with a sharp knife and then gently rinse the soil off the roots until they are fairly clean. The less soil you take into the system the better as it will serve no purpose. Dig a hole for the seedling in the growing medium to accommodate the root mass and place the seedling in the hole, filling it in gently around the roots. Try to fill the seedling in in such a way that the top of the growing medium is at the same level of the plant as the soil was originally. The seedlings will slow a little bit as a result of the transplant shock but should resume growing after a few days.

Growing Your Plants

As previously discussed the nutrient delivery is provided automatically by a simple little plug in timer available at most supermarkets or hardware stores and will be set to turn the pump on for 15 minutes every hour between 5am and 9pm. Apart from the more efficient control of the flood/aeration cycle active hydroponics have the advantage of automation when compared to passive hydroponics, which have to be hand watered. This system is going to be used outside so nature will control the photoperiod for us and we need not concern ourselves with timers for lights. This system will work just as well indoors of course with a growlight mounted on a gantry or suspended from the ceiling. Its construction makes it very leak proof and it would be ideal for indoor use.

Our Nutrient Strength Guide tells me that the vegetables we have selected, zuchinni, cucumber and silverbeet all grow with a nutrient strength around 18-25 with varying ph's not far from 7. The tank will be mixed for a cF of 22 and as this is intended to be a simpler system the only thing we will add to the tank is vegetative hydroponic nutrient solution to the prescribed strength and about 3ml of superthrive. When flowers begin to form we shall switch over to a flowering formula of nutrient at the same strength. If you were eager to squeeze that little bit extra out of these vegetables you could use pH lowering chemicals to reduce the pH to 6.3, which is considered to be the ideal for most plants. I suggest that those who are just starting out not worry too much about pH levels, assuming that you are using water that has a pH level of around 7. Dramatic shifts in pH levels will not do your plants any favours. I will add that I have used straight nutrient and ignored the pH level of my nutrient solution for years with no harm done, the plants seem to grow just fine. If I specifically want to have perfect growth I prefer to use a buffer such as Bio Earth Sea Acids, which will bring the pH down to the ideal and provide a few extra goodies as well.

It is a good idea to check the strength of the nutrient solution every two days or so. Being outside a good shower of rain will dilute the strength of the nutrient solution, in which case I usually just add more nutrient to bring it up to the required strength. In hot weather particularly but also at other times the water in your nutrient solution will evaporate but the nutrients themselves will not, resulting in a stronger nutrient mixture. When this occurs simply add more water to the tank until it is back to the required strength. Its usefull to add water or nutrient when the pump is running as this will mix your nutrient solution up for you. Wait a few minutes between measurements. Regardless of the weather its a good idea to change the nutrient solution every seven days or two weeks at the very most as the nutrient solution can become depleted of some elements more than others resulting in an imbalanced mixture. Empty the tank out completely, clean it as best as you can without using any form of detergent just fresh water and perhaps a sponge or scourer then refill it and mix a fresh nutrient solution.

Every month or so its a good idea when changing your nutrient to cycle fresh water through the system. Empty and clean your tank as usual and refill it with fresh water. Turn the pump on and leave it running continuously for about 24 hours. If you have a cF truncheon measure the nutrient strength of the water before you drain it out. You will find that the water may have a strength of somewhere between 4 and 8. This is because of the leftover nutrient salts trapped in the medium that running the pump continuously has loosened up and drawn out. Dump the water, preferably on something that will appreciate it like a tree or your flower bed, mix a fresh tank and resume the normal flood cycle.