Hello everyone,
3 years ago, I built a box and made a little modification for improving the soil aeration. I would like share this experience and maybe get some help for questions I have.
Description of my material:
box surface is 1.25m x 2.5m and 2.20m high (4.1 x 8.2 x 7.2 ft) (~3 m2 (32 ft2))
3 x 600 W HPS bulbs, 3 x 660 W electronic ballasts
ISO Max extractor, 1480 m3/h (871 cfm), 2000 m3/h (1177 cfm) filter.
32 x 11L (3 gal) square pots filled with coco
drain waste hydroponic
I use Canna Coco line (AB, Rhizotonic, Cannazym, PK 13/14, Canna Boost)
Soil aeration system
The modification is extremely simple: four boards of wood !
The idea is to part the box vertically at the level of the top of the pots. The air intake is at the bottom of the box and the exhaust at the top, so the air is forced to go between the pots and through the soil.
As the extractor is powerful enough, there is no need to pay too much attention for sealing it perfectly, the enveloppe of the box is naturally pushed against the external border of the boards due to the lower pressure inside the box.
Advantages
- The soil aeration is very effective, the proof is that the temperature measured in the center of the soil is 3-5°C (5-9 °F) under the temperature of the air intake, due to evaporation. When the air is dry and hot, the difference is often above 5°C (9°F) .
It's nice in summer but can be a problem in winter, so I always try to keep the soil over 20°C (68°F) by regulating the air coming from outdoors, otherwise the stems become red.
- The temperature of the box is usually around 2°C (3,5°F) lower than the air intake (lights off). It looks like a good thing, but I'm not sure it's really changing a lot because the air contains more humidity after passing through the soil and is then less effective for the evaporation of the leaves.
- One unexpected advantage is that I dont need fans inside the box, because there is one hole between every 4 pots (picture 2), 21 holes for the 32 pots. These holes are blowing vertically right under the leaves and quite strongly as you can see in this picture:
- I think that the heat evacuation is also more effective, because the air flow is more laminar, less mixing cold and hot air comparing to the use of fans inside the box.
- I suppose that this system can be used with any kind of soil, but never tried anything else than coco.
- The performance of the box is quite good, in 3 years I never made less than 0.75 g/W(0.0017 lb/W ; 0.0265 oz/W) with a highest yield of 1.24 g/W (0.0027 lb/W ; 0.0437 oz/W) with Master Kush. I don't use CO2.
I never did it without the boards with this box, so I have no comparison, but I'm happy with the results.
Disadvantages
- Because of the evaporation, the plants drink a lot, almost 10L/m2 (0.25 gal/ft2) per day during growing, more during flowering, and the nutrients are not cheap..
- As mentioned before, there is a risk of too low temperature of the soil in winter.
- The increase of humidity is nice during growing, but can be a problem during flowering. I usually open the biggest buds with my two thumbs for avoiding mold.
- The EC of the drain water is surprisingly high at the end of the flowering, sometimes above 5! I don't know what to do with this, and that's my question. I suppose that it's due of the evaporation concentrating the nutrients. It's not a problem, as everyhing is green until the last moment, but I would like to try to improve it.
I wonder if I would get even better results by draining more the soil or by concentrating less the nutrients so that the EC stays under 2.5.
At the opposite, there is a possibility that the extra O2 in the soil improves nutrient absorption, so I would like to try how much more nutrients the plants can get before suffering.
I didn't try CO2 yet, but as people say that roots are also able to absord it, I can't wait !
Any comments will be appreciated, why not trying it yourself ? I would be very curious of others experience.
(and sorry for the metric system)
Regards
3 years ago, I built a box and made a little modification for improving the soil aeration. I would like share this experience and maybe get some help for questions I have.
Description of my material:
box surface is 1.25m x 2.5m and 2.20m high (4.1 x 8.2 x 7.2 ft) (~3 m2 (32 ft2))
3 x 600 W HPS bulbs, 3 x 660 W electronic ballasts
ISO Max extractor, 1480 m3/h (871 cfm), 2000 m3/h (1177 cfm) filter.
32 x 11L (3 gal) square pots filled with coco
drain waste hydroponic
I use Canna Coco line (AB, Rhizotonic, Cannazym, PK 13/14, Canna Boost)
Soil aeration system
The modification is extremely simple: four boards of wood !
The idea is to part the box vertically at the level of the top of the pots. The air intake is at the bottom of the box and the exhaust at the top, so the air is forced to go between the pots and through the soil.
As the extractor is powerful enough, there is no need to pay too much attention for sealing it perfectly, the enveloppe of the box is naturally pushed against the external border of the boards due to the lower pressure inside the box.
Advantages
- The soil aeration is very effective, the proof is that the temperature measured in the center of the soil is 3-5°C (5-9 °F) under the temperature of the air intake, due to evaporation. When the air is dry and hot, the difference is often above 5°C (9°F) .
It's nice in summer but can be a problem in winter, so I always try to keep the soil over 20°C (68°F) by regulating the air coming from outdoors, otherwise the stems become red.
- The temperature of the box is usually around 2°C (3,5°F) lower than the air intake (lights off). It looks like a good thing, but I'm not sure it's really changing a lot because the air contains more humidity after passing through the soil and is then less effective for the evaporation of the leaves.
- One unexpected advantage is that I dont need fans inside the box, because there is one hole between every 4 pots (picture 2), 21 holes for the 32 pots. These holes are blowing vertically right under the leaves and quite strongly as you can see in this picture:
- I think that the heat evacuation is also more effective, because the air flow is more laminar, less mixing cold and hot air comparing to the use of fans inside the box.
- I suppose that this system can be used with any kind of soil, but never tried anything else than coco.
- The performance of the box is quite good, in 3 years I never made less than 0.75 g/W(0.0017 lb/W ; 0.0265 oz/W) with a highest yield of 1.24 g/W (0.0027 lb/W ; 0.0437 oz/W) with Master Kush. I don't use CO2.
I never did it without the boards with this box, so I have no comparison, but I'm happy with the results.
Disadvantages
- Because of the evaporation, the plants drink a lot, almost 10L/m2 (0.25 gal/ft2) per day during growing, more during flowering, and the nutrients are not cheap..
- As mentioned before, there is a risk of too low temperature of the soil in winter.
- The increase of humidity is nice during growing, but can be a problem during flowering. I usually open the biggest buds with my two thumbs for avoiding mold.
- The EC of the drain water is surprisingly high at the end of the flowering, sometimes above 5! I don't know what to do with this, and that's my question. I suppose that it's due of the evaporation concentrating the nutrients. It's not a problem, as everyhing is green until the last moment, but I would like to try to improve it.
I wonder if I would get even better results by draining more the soil or by concentrating less the nutrients so that the EC stays under 2.5.
At the opposite, there is a possibility that the extra O2 in the soil improves nutrient absorption, so I would like to try how much more nutrients the plants can get before suffering.
I didn't try CO2 yet, but as people say that roots are also able to absord it, I can't wait !
Any comments will be appreciated, why not trying it yourself ? I would be very curious of others experience.
(and sorry for the metric system)
Regards
