It's called S/H because it is not a linked system with a shared reservoir/water source, as in hydroponics. Think passive hydroponics on a single pot scale.
The hole is for two reasons: 1. to make sure you don't over-fill the reservoir. Ray recommends refilling the pot by filling it with water to the top and letting it flood/drain out the hole. This limits salt buildup which can otherwise affect S/H if you only fill to a certain height each time.
2. If you don't have the hole you have no way of flushing the pot, which is very necessary.
The wick isn't necessary because the LECA wicks. Ordinary organic potting media would break down under constant moisture introducing rot and suffocating the roots. Hence the requirement for an inert, inorganic media with all hydro/semi-hydro systems.
Quote:
Originally Posted by tokyo
Ok, here's a crude drawing of what I am thinking of doing.
This is if I went the route of using LECA instead of standard potting medium and a wick system.
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I think your idea is a great one and in theory should work well with adjustments.
I have a couple of years experience using a system that is identical, except that i hadn't used the upturned bottle for automated re-filling, and i use many pots instead of just a single one. I had used decives called the
Smart Valves Mk II refilling separate trays via a gravity fed reservoir.
This is an old picture of my shelf system, you can see the black trays that hold the water and the individual white pots. I use perlite instead of LECA but the two are interchangable. The reservoir is out the window.
http://img33.imageshack.us/img33/1860/systemsmall.jpg
As you can see root growth is very good, especially the roots that form completely under-water. There is no need whatsoever to keep the root zone above the water line, in fact for good culture i recommend keeping part of the root zone submerged. You will be amazed how well an orchid root takes to life underwater (once it adapts!!)
http://img713.imageshack.us/img713/8228/4small.jpg
http://img130.imageshack.us/img130/3917/underwaterw.jpg
I faced a few problems with the system though:
1. You will want to use pots without drainage holes, or at least only a single small hole at the base to allow the water to seep in. If you use a normal pot, the roots will grow straight through the holes and into the shared reservoir and potentially into other pots if you put more pots in there. At the very least it's a major pain to repot because the escaped roots will not fit back into a pot shape and need to be cut off.
2. The shared reservoir will get bad algae growth everywhere that is moist and exposed to light. The area in the tray not covered by the pot or feeder bottle in particular will become an algae pond. You can get around this by minimising the parts exposed to light - square pots work particularly well if you use more than one pot.
3. You MAY have a real problem with virus and disease transmission if you use more than one pot. There is conflicting evidence on this, but certainly it has been shown in many studies that all the major viruses are spread within hydroponic systems within a week of a single infection. Jury is out whether it would be a major problem in a system that limits flow and recirculation, like this one. There are studies suggesting it wouldn't, but i think it's definitely possible. I have not had any problems after about 3 years.
The above 3 reasons are why S/H is preferred by most people over this sytem. The roots are always contained within a single pot, algae growth is limited to the pots themselves and disease cannot spread.
Basically if you have tonnes of pots (and willing to risk the threat of virus spread - which most people aren't), I think your (my) system is a good option. It saves a HELL of a lot of time watering. But If you just have one pot or a small collection, Ray's S/H method is simpler and just as effective.