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DIY Hydroponics - Using a Top Feed Hydroponic System

Potting up for top feed hydroponicsIn this section lets examine the use of the top feed system we constructed on our Building a Top Feed Hydroponic System page. The methods described here can be applied to any top feed system and a lot can apply to a flood and drain system too. I personally feel that a top feed system is slightly better than flood and drain because the nutrient solution is applied at the base of the plant and is allowed to cascade over the plant roots allowing more of the media in the pot to be utilized.

We are using the capsicum seedlings that we started for the Starting Seedlings for Hydroponics page and of course the objective is to bring them to fruition so that novice hydroponic gardeners can see the seedlings progress through their entire life cycle.

Potting Up the Seedlings

The capsicum plants are still in the seedling stage of growth and have several sets of green healthy leaves and the root systems have outgrown the rockwool cubes they were germinated in. They are most certainly ready for potting up and moving into the main hydroponics system where they will complete their life cycle.

A 180mm pot is adequate for a capsicum plant however if you have the space and the inclination a 250mm pot might be slightly better. These particular seedlings will be placed into a larger rockwool cube but the majority of the pot will be filled with hydroclay, an expanded clay made specifically for hydroponic gardening. The top feed system is not just limited to hydroclay, you can use perlite, perlite and a rockwool cube like the one we're using here, rockwool by itself, coconut fronds or peat. In fact most hydroponic media can be used in top feed systems successfully. Wash your media before you use it. Soak and rinse rockwool and rinse any other media you might be using thoroughly.

Following our photos to the right we can see the first picture is simply the empty 180mm pot. Make sure it is clean, particularly if it is not new. We dont want the blight that reduced the last yield being carried over to this season. On the next picture we have filled the pot with enough hydroclay so that the rockwool cube sits roughly level or slightly below the top of the pot. Place the rockwool cube into the pot and then fill around the sides of the cube so that it is supported against the side of the pot by the hydroclay. Seedling cubes are generally a neat fit into the larger rockwool cube, ease the seedling into the larger cube gently but firmly so the seedling cube is sitting snugly in the grow cube.

Our little seedlings are now ready to move into the hydroponic system.

Insert the dripper
Place the freshly potted up seedlings into position in the tray. Insert the dripper as pictured so that the dripper is slid carefully between the seedling cube and the larger rockwool growing cube. You will have to gently wiggle it when the dripper spike reaches the hydroclay to make sure the spike goes all the way down.

Growing Your Plants

The nutrient solution delivery and lights are controlled by plug in timers that are readily available at most supermarkets and hardware stores at a modest price. The timer is not really necessary if you are prepared to turn your pump on and off several times a day at the appropriate intervals and turn the lights off and on every day but it sure makes your life easier just to automate it using these simple timers.

Capsicums are not dependant on photoperiod, that is they dont generally need the day length changed from eighteen hours to twelve to trigger fruit production, if your chosen crop requires this then once the plants reach about 30cm (1 foot) in height change the timer to reflect your chosen day length. Our timer is set to turn the lights on at 6am and off and midnight. As we are using a flourescent light the distance between the light and the tops of the plants will be kept at around six inches or so.

The regime for the nutrient solution is perhaps a little more complex. Our Nutrient Strength Guide tells us that capsicums like a nutrient strength of 18-22cF (1260-1540 parts per million) and a pH of 6.0-6.5. The initial tank we have mixed contains 10ml/litre Bio Earth Sea Acids which brought the pH down to 6.2 and the cF to 10. Nutriflo Vegetative nutrient solution was added at about 3ml/litre to bring the nutrient strength cF to 20. I also add about 3ml of Superthrive which the plants really seem to love. This will be the mainstay of the plants diet until they begin to set fruit, at which point the we will change from a vegetative solution to a flowering solution whilst keeping the sea acids and the superthrive at the same dosage.

Seedlings in a Top Feed Hydroponic SystemThe strength of the nutrient solution must be measured at least every 2 days or so with a cF truncheon particularly if your growing room is hot. The water will evaporate from the hydroponic system resulting a much stronger mix than the plants can stand over an extended period. When the nutrient starts to get too strong add plain water to it to dilute it. Over time the nutrient solution will become depleted and should be changed. I recommend changing the nutrient solution every seven days however you can probably stretch it to two weeks at a pinch. Change it every seven days and the plants will be so much better for it.

The final consideration for your top feed system is the delivery of nutrient solution. This requires some fine tuning depending on several factors such as the temperature and humidity of your growing environment and what hydroponic media you are using. I live in a temperate environment but summers are very hot here and my media can dry out very quickly on a hot summers day. The regime we will use for our capsicums is to have the nutrient pump timer set to pump for fifteen minutes at four hour intervals when they are small and fifteen minutes at three hour intervals when they reach about twenty centimetres in height. I dont set the pump to run at all during dark hours (when the lights are off) unless there is a heatwave. If you were using perlite or rockwool as your medium you might run your pump at five or six hour intervals as rockwool and perlite retain water longer than hydroclay does. The pumping interval really depends on your environment and fine tuning can result in higher yields and bigger better plants. Experiment and write down what results you have achieved at what intervals and you will soon get the hang of it. Keep an eye on your media and make sure it never completely drys out.

Finally, a pedestal fan or desktop fan is a fantastic way to keep the air moving in your hydroponic system. Keep it at a distance so the plants leaves move in a gentle breeze. Reflective mylar or some sort of reflective surface around the perimeter of the growing area will increase the intensity of your lights by reflecting light that would otherwise be wasted back into the growing area. There is no mylar around this system because it reflects the flash of our camera and ruins our pictures!

Just a few weeks later our capsicums are doing fine.