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Step 10Disinfecting and Filling the Reservoir
The Nutrient Reservoir can become quite a utopia for all sorts of nasty microorganisms that can wreak havoc on your plants. If I've only learned one thing from my years working in microbiology labs it's that they are persistent little buggers. If you give them half a chance they will take over your entire setup in no time flat. There's no way that you can completely suppress them, but you can prevent them from flourishing with a few simple preventative measures.
First of all, the reservoir and growth medium has to be disinfected prior to use. All you need is a bathtub, some hot water and some chlorine bleach. The clay pellets a covered in dust before their first use so I rinsed them off before filling each mesh basket with them (Figure 10B). I laid all six mesh baskets in the empty reservoir and then added a generous portion of chlorine bleach. I filled the reservoir with hot water and let the whole thing sit for about an hour. Then I gave everything a quick rinse and it was ready to be filled.
The water level here is important. At first the roots probably won't be sticking out of the rockwool cubes so you should fill the reservoir up to soak the cubes directly. As the roots grow down it is necessary to lower the water level until there is a small gap between the surface of the water and the bottom of the mesh pot. The roots should have to pass through a small air space between the pot and the solution.
Now to prepare a good nutrient solution, a few skills in mathematics are required. Most hydroponics nutrients come in a very concentrated form that must be diluted before the plant can use it. The bottle should give you an amount of nutrient to mix with an amount of water (Figure 10C). As you can see the nutrient comes in three parts that must be mixed in different proportions depending on the stage of the plant's growth. The bottle only lists how much of each nutrient to mix with 100 liters of water. Since my reservoir does not hold that much I need to come up with an equation that generalizes how much I need to add to any volume of water.
Vn = (Vr/100L) x Vb
Where:
Vn = Volume of nutrient needed (ml)
Vr = Volume of water in reservoir (L)
Vb = Volume of nutrient per 100L as listed on bottle (ml/100L)
For example, when I first filled my reservoir I used 14 liters of water to accomidate my plants through the vegetative growth stage. The amount of nutrient listed on the bottles were:
FloraGro: Vb = 396 ml/100L
FloraMicro: Vb = 264 ml/100L
FloraBloom: Vb = 132ml/100L
Therefore the volumes of nutrient I had to add to my reservoir were:
FloraGro = (14L/100L) x 396ml/100L = 55 ml
FloraMicro = (14L/100L) x 264ml/100L = 37 ml
FloraBloom = (14L/100L) x 132ml/100L = 18 ml
Of course, all of these volumes have to be measured accurately. For the water I used a measuring cup and for the nutrient I used a syringe. A pen, some paper and a calculator also comes in very handy when doing this task (Figure 10D).
First of all, the reservoir and growth medium has to be disinfected prior to use. All you need is a bathtub, some hot water and some chlorine bleach. The clay pellets a covered in dust before their first use so I rinsed them off before filling each mesh basket with them (Figure 10B). I laid all six mesh baskets in the empty reservoir and then added a generous portion of chlorine bleach. I filled the reservoir with hot water and let the whole thing sit for about an hour. Then I gave everything a quick rinse and it was ready to be filled.
The water level here is important. At first the roots probably won't be sticking out of the rockwool cubes so you should fill the reservoir up to soak the cubes directly. As the roots grow down it is necessary to lower the water level until there is a small gap between the surface of the water and the bottom of the mesh pot. The roots should have to pass through a small air space between the pot and the solution.
Now to prepare a good nutrient solution, a few skills in mathematics are required. Most hydroponics nutrients come in a very concentrated form that must be diluted before the plant can use it. The bottle should give you an amount of nutrient to mix with an amount of water (Figure 10C). As you can see the nutrient comes in three parts that must be mixed in different proportions depending on the stage of the plant's growth. The bottle only lists how much of each nutrient to mix with 100 liters of water. Since my reservoir does not hold that much I need to come up with an equation that generalizes how much I need to add to any volume of water.
Vn = (Vr/100L) x Vb
Where:
Vn = Volume of nutrient needed (ml)
Vr = Volume of water in reservoir (L)
Vb = Volume of nutrient per 100L as listed on bottle (ml/100L)
For example, when I first filled my reservoir I used 14 liters of water to accomidate my plants through the vegetative growth stage. The amount of nutrient listed on the bottles were:
FloraGro: Vb = 396 ml/100L
FloraMicro: Vb = 264 ml/100L
FloraBloom: Vb = 132ml/100L
Therefore the volumes of nutrient I had to add to my reservoir were:
FloraGro = (14L/100L) x 396ml/100L = 55 ml
FloraMicro = (14L/100L) x 264ml/100L = 37 ml
FloraBloom = (14L/100L) x 132ml/100L = 18 ml
Of course, all of these volumes have to be measured accurately. For the water I used a measuring cup and for the nutrient I used a syringe. A pen, some paper and a calculator also comes in very handy when doing this task (Figure 10D).
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Nov 10, 2008. 12:52 AMlittleangels
says:
WOW! I am completely impressed! Just starting to investigate hydroponics, you make it seem so simple! ( I am sure that is a "ha-ha"). Where I live, (USA, on west coast, no sun), is in an agriculture belt, but alas, I can't even grow tomatoes...no sun, too many pine trees...So, this seems perfect! If you ever want seeds, I have been collecting organic seeds for many years, have LOTS, and am willing to share. Pumpkins, Italian Butter beans (really good), all the way to pears, apples, persimmons and tangerines. Let me know if you would like any seeds to experiment with. How would fruit trees do in hydroponics?
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Jun 29, 2009. 6:02 PMbabybackribs
says:
um...i'm gonna have to say that fruit trees get way too big for hydroponics even before they are ready to bear fruit. I have just purchased 6 seedlings that are about 6 feet high and in 4 gallon planters that won't produce fruit for at least a few years until they are well established in the soil. I guess it's possible on a huge scale, but not practical.
Reply
Apr 2, 2009. 1:23 PM2cardGUTZ
says:
its called mylar, reflects 95% of light, use it. believe it or not aluminum foil @ 50% and yes flat white is a better option better than foil
Reply
Jan 19, 2009. 2:18 AMSixTwelve
says:
I really enjoyed the article. I'd like to share one project suggestion and one article suggestion. Project: Instead of painting the reservoir lid white, you might consider aluminum foil. Spray tack doesn't cost any more than paint, and for that matter flour paste would likely bond foil to the plastic irretrievably, and practically for free. Article: I understand you recommended an understanding of Ohm's law. The thing is, laypersons tend to over-estimate their safety in this area. I only point this out because a 50% safety barrier is generally considered minimum in the industry. You did this and more with your example wiring; I would suggest spelling that out, though. Thanks for an entertaining and informative read!
Reply
Feb 28, 2009. 7:32 PMAsianSpanker
says:
I read somewhere that flat white reflected back as much light as aluminum foil. Or that the difference was so small that it was not worth doing expensive reflector systems. But that was 10 years ago. We be some more smarter now.
Reply
Feb 19, 2009. 2:55 PMkd1s
says:
I have to build this. The electricity usage is pretty low and having fresh veggies and other items throughout winter would be nice. I understand plant nutrition so there isn't a barrier there.
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