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Rice Hulls


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Old 05-09-2010, 05:52 AM
le0n le0n is offline
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Default Rice Hulls

Hi Guys,

Been slowly getting my system ready and was going to use Rice Hulls as the growing medium because I can get an unlimited free supply here in the Philippines.

Was fine tuning my system as a top feed flood using sprays and drain out the bottom but had lots of problems with the Rice Hulls getting into all the tubes, Sprays, filters and pumps.

Then I found I can purchase Hydroton in Manila from an aquirium supply house and have now changed back to a basic flood and drain system. Have two 50 litre bags on the way. Testing so far is giving me satisfactory results however I've yet to try my system with the Hydroton and also any actual plants. Returned from Australia with some very healthy Strawberry plants.

When cleaning my growing pots which are about 200mm deep I noticed the Rice Hulls were still quite wet about 20 to 25% from the bottom. This was after not being watered for over a week. Tells me that Rice Hulls in a grow pot that deep may not be a good growing medium and maybe could have given root rot problems. Had I not been aboe to obtain the Hydroton I would have tried Coconut fibre next, also available here cheap and easy.

Cheers Leon...

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Old 05-09-2010, 06:40 AM
GpsFrontier GpsFrontier is offline
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When cleaning my growing pots which are about 200mm deep I noticed the Rice Hulls were still quite wet about 20 to 25% from the bottom. This was after not being watered for over a week. Tells me that Rice Hulls in a grow pot that deep may not be a good growing medium and maybe could have given root rot problems. Had I not been aboe to obtain the Hydroton I would have tried Coconut fibre next, also available here cheap and easy.
200mm (or 20 cm, about 8-9 inches) is not deep to me. A lot depends on good drainage in the system. Did the system design allow for every inch of water to drain out the bottom in-between watering cycles? A lot also depends on how compact (packed) it becomes also. Coco fiber is commonly used in hydroponics, but unless the system drains well it can be a problem also (anything can be if it doesn't drain well). Some material holds moisture better than others (like coco fiber, and the husks), It can be beneficial because of it.

But if it's packed down to tightly (not allowing enough air to penetrate to the bottom and/or throughout it), it can also be a bad choice, especially if it doesn't have very good drainage. The more it packs down, the less air will be able to penetrate, and it won't be able to drain well regardless. I had 5 gallon buckets with coco "chips" in it (about 2 1/2 feet deep) but the drain was at the bottom and held less than 1/2 inch left at the bottom between cycles. Also at the bottom there was about 3-4 inches of plain rock (cleaned and sterilized) for weight and drainage. Also if pipes, tubes and filters tend to get clogged, that will block drainage as well.
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Old 05-09-2010, 11:22 PM
le0n le0n is offline
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Hi GPS, looks like you totally missed the point I was making and this is. After a week of no watering the bottom 20% of the 8" deep Rice hulls were still full of moisture. Far too much moisture in my opinion. Not damp but very wet. The Rice Hulls were only compacted as normal.

Maybe the humidity here in the Philippines could have some thing to do with it.

Regards Leon...
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Old 05-10-2010, 02:15 AM
GpsFrontier GpsFrontier is offline
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Hi GPS, looks like you totally missed the point I was making and this is. After a week of no watering the bottom 20% of the 8" deep Rice hulls were still full of moisture.
Sorry, moisture is not the problem. Lack of air/oxygen to the root system is. Plants need moisture all the time, and with a root system in the containers they will suck up moisture all the time. If a container is sealed off enough (not enough air circulation) the water will never evaporate regardless of how long it has been there, weeks months or even years. Water will naturally drain (south/down) unless it cant. That would be a lack of good drainage, then it pools or puddles up, and it may take years to evaporate without air circulation. That would be a compact soil (or growing medium) not allowing proper air circulation in order for it to evaporate and drain.

I have not used rice hulls for a growing medium, and I don't know what you mean by only compacted as normal. Even soil can become too compacted and not allowing good drainage (air circulation to the root system). Even when not compacting it at all. Over time it will expand and settle down, this takes away the air passages that provide the air circulation/evaporation. Humidity or not, if there was adequate air circulation to the bottom of the containers they would not be soaked (unless it has rained).

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