Not an expert on this at all, but I would think ammonia shouldn't be present unless you have recently stocked fish and the water hasn't cycled yet. If the system receives light (which I assume it does) you should have decent levels of nitrate.

The question would be whether various minerals would be present. Are there rocks in the system? Also, the type of orchids you are growing would be relevant.

More info.

Jane

Hi
Well the "wall is 7x10 ,located in the shadehouse mad mostly of expanding foam. Water from the 5x10 foot lily pool runs down this wall ,collects into a Marsh garden flows into a 150 gallon aquarium then flows back to the pool. Both the aquarium and the pool have both plants and fish. The epiphytes are located on the wall . The orchids are Catts, Dends, Phals,Paphs. and epidendrums. there are also several types of Brom,ferns and philos. as well as some succulents,epicactus. Obviously a lot of things pulling nitrate from the water.lol The system has been setup for the second year this May Everything has done well
with the exception of overgrowth lol. The growth rate ,particularly of the vines and marsh plants has been unbelieveable..
I have only cheap test kits but you only have to look at the plants and fish to see the system is functioning very well. The Ammonia,Nitrite check zero while nitrate is less than 30 PPM.
I would like to get some good test kits but I'm not sure what I want to test for ?? lol
Haven't added any ferts to the wall as obviously this would wash down into the water areas . Would rather error on too little than too much. ??
I suspect that trace minerals are rather scant as the system has an automatic changer using rainwater. The pH has remained from 6.5 to 7 very consistantly in spite of the drought.
i have kept both water gardens and orchids for many years but never together lol Excesses were never a problem.
I certainly thank you for the help!!! gary

Sounds great. I don't think you need to test for anything. Sounds like the system is balanced. As far as the plants, the only thing which might be missing would be the trace minerals which could be handled with the addition of some rocks. Your pH is good so you would have to be careful what type of rock you would add.

I would think the hydroponic people could help. Instead of fooling with rocks there are mixes which could add the trace minerals. Water plants are good nitrogen feeders and keep it in check. Keep an eye on your nitrogen.

I agree, you shouldn't add any fertilizer, just traces.

Jane

Jane
I used top soil covered with acrylic chips and aquarium gravel for the planting bed in the aqarium. In the pool the lilies are potted in fracted clay. I use fetilizer spikes on them . So obviously along with the nitrogen cycle I'm also getting at least a little fert as well as trace minerals. to the epiphytes. I had to redo the pool this spring due to an invasion of brazillian pepper so put in a new liner . It is a brilliant green lol. I had to use tap water as it holds 1000 gallons . It is isolated from the rest of the system until the nitrogen cycle kiks and or I get enough rain water to bring the pH down.
i asked on the hydroponics forum but nobody was familiar with epiphytes. There are several aquaponics sites but again none deal with epis.
Among the orchids the only one that is not doing well is a Paph, but I think it's more of a light than media or water problem.. With all that growth the light patterns are changing constantly not to mention the seasons lol.
I think for right now I'll do nothing and look for
signs from the plants. Chemistry is definitely not my strong suit lol. In another couple of weeks the entire system will be reconected and see what happens.
Thanks very much for the help. gary

Sounds wonderful, I'd love that. I used to have salt-water tanks, the largest 150 gal. It was tricky keeping the water chemistry stable and I learned alot along the way. Chemistry is not my thing either, but its do or die with salt water.

I had smaller reef tanks where I had invertebrates, mostly corals and sponges. The larger tanks were a mix with some fish and plants. Was a lot of work but I loved it.

I started with fresh water years before and grew into salt. I can't be of any help growing orchids that way except if they aren't kept soaking wet, it sounds great. Of course the more sunlight, the faster the water plants will grow. You need the light for the orchids, but have to watch the growth on the water plants. Its all a balance to keep the water stable.

I don't think the orchids will be the problem. Keeping the water plants under control might be. Get fish which will eat some vegetation so you don't wind up with overgrowth.

Good luck and post some pics. I'm soooo jealous!

Jane

Hi
Well the pond has stabilized as shown by the explosive growth of the hyacinth and the lily has stated to climb out lol The nitrogen level has risen to around 125 and I think it's time to reconnect the systems. The aquarium has remained at under 30PPM but of course will rise when the water mixes.
I made up some standard fert mix and the N level is around 75 using distilled water as the base. So 125 may be a bit strong for the epis??
Have been unable to find any references to "ideal" levels for orchids . I've always followed the "Weakly weekly" regimen and followed the usual methods of application . Maybe I should start off by mixing the aquarium and pond water and isolate the "falls "until I find how stable it is?? I moved two Catts and a paph off the wall that were showing signs of stress but more to light than fert in my opinion. I don't think it's possible to over fertilize water and marsh plants as long as the pH is stable but Epi's I'm not sure lol.
The 150 aquarium is my old reef tank. Went 38 days without power during the hurricanes so the reef "tanked " so to speak. decided to get out of SW altogether. Since you can't have a waterfall without a reservoir decided to use it and it has worked out well. Of course there is NOTHING as beautiful as a healthy reef tank.
Thanks again for your help!!!! gary

Sounds great! You can over fertilize and get too much green growth. Cuts way back on the oxygen and you lose the fish. But with the waterfall, you should be okay. Don't know about the Epi. As long as their roots are getting plenty of air and sunlight, they may do well.

Good luck, and keep us posted

Jane