[littlefrog]

Originally Posted by Silent Running

Thanks for the info folks. I'll try the aquarium water and see how it goes. I have to add KNO3, KH2PO4 every other day to maintain the nitrate and phosphate levels in the tank, as well as the trace elements. I add K2SO4 for potassium weekly to the water. I guess my thinking is that it's more than just the fish waste that will be feeding the plants. I'll let you all know how it goes.

It is certainly better than no fertilizer... Plenty of nitrogen and potassium. Orchids are light feeders, but they still need phosphorus, calcium, magnesium, manganese, and a host of other things too. In small quanties. These things may be present in your water. Just to be safe though, I'd probably use a more defined fertilizer (dyna grow, or peters, or there is a 'new' thing from Michigan State U that works pretty well) at least once in a while. Every couple of months, maybe. Chances are good that you would never see a micronutrient deficiency, but it is good cheap insurance.