Is Planted Aquarium Water OK for Orchids?

[Silent Running]

I have a fully planted 100 gallon fresh water aquarium that I perform weekly water changes on. I maintain nitrate at 10 ppm, phosphate at 1 ppm and potassium at roughly 15 ppm. I also add trace elements and iron to the water as well. My question is whether or not the water from this tank can be used for watering my new (and first) orchid (phalaenopsis). I use the water for my other house plants and they do really well with it, but I'm not sure if it's appropriate to use on an orchid. Any input would be appreciated.

[Tindomul]

I have often thought the same, I would use aquarium water to water the plants, I never saw any results, but I would consistently use it either. I would assum that all the nitrates etc.. in that kind of water would actually fertilize plants.

[littlefrog]

Originally Posted by Silent Running

I have a fully planted 100 gallon fresh water aquarium that I perform weekly water changes on. I maintain nitrate at 10 ppm, phosphate at 1 ppm and potassium at roughly 15 ppm. I also add trace elements and iron to the water as well. My question is whether or not the water from this tank can be used for watering my new (and first) orchid (phalaenopsis). I use the water for my other house plants and they do really well with it, but I'm not sure if it's appropriate to use on an orchid. Any input would be appreciated.

Aquarium water is fine for orchids. Saltwater tanks excluded, of course. You may be tempted to rely on the fish waste in the water to fertilze your orchids, but I'd try to avoid that. The fish waste won't hurt anything, but you will still need to fertilize your orchids with a good complete fertilzer, at least occasionally. All of your houseplants would probably like a little plant food.

Rob

[jbeetle]

I have used tadpole water (from raising dart frogs) to water my orchids and other tropical plants. It worked great. I had a lot of flowering as well as growth, and I didn't use any other fertilizers.

[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.

[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.