Aquaponics & S/H?
 

I've been seeing some beautiful setups on the internet that involve plants growing out of the tops of fish tanks. Would this be possible to do with orchids, maybe with pots of hydroton that are submerged an inch or two into the tank?

I currently have a paludarium that is mostly dedicated to orchids, and I'm percolating an idea for an exposed, indoor drip wall that drains into a fish tank, with a cool rock formation and lots of lithophytes up top, and maybe a few orchids in S/H right near the tank. Something like this + this.

Part of my reasoning is that I'm great at building things and tinkering, and good at growing orchids inside a tank, but much less good at consistent watering by hand. Plus, of course, I think it would look great and would add some humidity to my extremely dry high desert air (I'm sure I would have to top off the aquarium water or the reservoir more than once a week). I would also love to grow a few Phrags and an Angraecum sesquipedale, which I've heard do well in S/H. I'm assuming that I would have to supplement the fertilizer from the fish with a fish-safe plant fertilizer.

You could figure out some way to float containers in the tank easily. Aquaponics growers here float foam cooler chests in ponds and grow vegetables in them.

The issue would be providing enough light for the orchids. At those light levels you will have huge algae growth in your tank unless you use CO2 and have a lot of aquarium plants.

That's a valid consideration, but one I have some experience with due to my paludarium - I have Cattleya light at the top, 12+ hour days, and enough light hits the water section that I had a serious algae bloom for the first few months. It has evened out now, and there's no noticeable algae in the water. I think with a combo of plants in the tank + floating plants providing shade, I could manage Angraecum-level light. Not sure about phrags.

Lighting in general is going to be interesting, because I'm thinking about having a 2' wide x 4' high rock drip wall above the aquarium, so I could either hang a grow light at the very top and then by the time you get to the aquarium it's like 500 footcandles, or mount lights along the sides - not sure how to go about that.

Maybe side lighting would help with the aquarium light issue, but I have no idea how plants respond to that - would they grow sideways?

They definitely grow towards the light. If I have Cattleyas too far from the windows in my sunroom they grow out straight horizontally.

this first picture looks like it could work, the second picture would not work too well for most orchids long term imo, would be great for the first year if they are small to start them off.
This thread has covered something similar, have a read through it http://www.orchidboard.com/community...humidity+night

You would not need to feed the orchids if there are indeed fish in the system. Orchids are light feeders and fish would provide all they needed in their waste.

Isn’t the point of S/H to keep the bottom inch or two of the pot constantly in water so the clay aggregate can wick water up around the roots?

yes and depending on the orchid you might need to repot it once the roots grow into the water. Phals can generally handle being in standing water more than others but I try to avoid it as much as possible. It's a bit of personal preference so take my comment as such. I haven't lost an orchid due to too wet roots but it slows growth down. The challenge is not keeping them too wet or too dry. I have seen orchids stall growth and resume it under better conditions.

If it's S/H and the plant grows its roots into the water opposed to them being placed in the reservoir area during potting, it's perfectly fine. The slow down in growth in wet conditions could be due to evaporative cooling, in which case a heatmat would help. Sounds like you are talking about convential growing and not S/H?

If you grow orchids in the “floating S/H” setup, I guarantee the roots will grow down into the tank, and there is absolutely nothing wrong with that unless that are nibbling fish in the tank.

Great, it sounds like in theory, suspending the orchids above the tank with an inch of pot in the water would work well, and I would just have to adjust light levels until I get a good balance with algae. Sounds like I also will want to keep temperature in mind, and it might work best for orchids that like cool feet, due to evaporative cooling.

Doing some further reading, it seems that S/H might not be ideal for extremely dry environments, since there can be a large difference in humidity between the bottom of the pot and the top. Does anyone have experience with this? I currently have hydroton, is there any material I could use in addition or instead that would help with moisture distribution?

I have had issues with evaporative methods of growing before, for instance I haven’t had good luck with Kool Logs because the moisture wicking just can’t keep up with my dry air. Then again, I may have had the wrong expectation - it was years ago at this point and might be worth another try.