Fish tank water for orchids?

[mheleo]

I have two large fresh water fish tanks (75 & 150 gallons) and as part of its maintenance I do partial water changes every week. I hate to dump the water which is rich in nitrogen (40 ppm of nitrates) and fish wastes. In the summer time, I use it to water the lawn and my vegetable garden. Just wondering if I can use it to water my orchids. What do you guys think?

[MrHappyRotter]

Yes, it's probably safe. Particularly if you have an idea of the water parameters (i.e. TDS, pH, nitrates, hardness, etc).

Keep in mind that aquarium water is usually pretty "dirty" compared to the water quality that many epiphytes would receive in nature, so you might consider mixing the tank water in with RO water and consider it a weak fertilizer.

The tank water is also probably a lot safer to use on standard terrestrial house plants, and as you mentioned, in the garden. But, I've never had problems that I can attribute to aquarium water when used on the orchids.

[mheleo]

Originally Posted by MrHappyRotter

Yes, it's probably safe. Particularly if you have an idea of the water parameters (i.e. TDS, pH, nitrates, hardness, etc).

Keep in mind that aquarium water is usually pretty "dirty" compared to the water quality that many epiphytes would receive in nature, so you might consider mixing the tank water in with RO water and consider it a weak fertilizer.

The tank water is also probably a lot safer to use on standard terrestrial house plants, and as you mentioned, in the garden. But, I've never had problems that I can attribute to aquarium water when used on the orchids.

Thanks MrHappyRotter. I will dilute it with RO water.

[Paul]

Don't know that dilution is necessary. Do keep in mind that you may NOT want to try this during the winter or if you are a strictly indoor grower -- unless you REALLY like having your home smell like a wharf after the fishing boats have returned.

[maelstrom mike]

Originally Posted by Paul

Don't know that dilution is necessary. Do keep in mind that you may NOT want to try this during the winter or if you are a strictly indoor grower -- unless you REALLY like having your home smell like a wharf after the fishing boats have returned.

Haha,

This reminds me of when a professor discussed using fish emulsion on organic transplants and I thought it sounded like a good idea. Of course, this was my very first time growing seedlings inside and yes it was the middle of winter. My apartment smelled like rotten fish for several days. He later reviewed what I did and replied, "I hope you didn't do that inside!"

I would agree and think it's safe to use for orchids depending on if you add any chemicals to the tank. You just might want to alternate with some pure water once in a while.

[Leafmite]

I have to winter my goldfish indoors in their tub. I toss the mounts in the tub at night to soak. Those orchids are really thriving.
When I have to do a partial water change, I do water my plants with the water. Fortunately, it isn't too bad.
During the summer, I often add powdered milk to my watering can for extra calcium. It is another of those things that just should never be done inside.

[mheleo]

Thanks for the advise guys. I think, I will alternate between the two.

[soobie]

I use straight fish tank water all the time, and I grow my orchids (and other house plants) inside. No bad smell, ever. If the tank is well maintained, it won't stink.

[Subrosa]

If you can safely use the source water that you use to fill the tank, you can probably use water from the tank safely as well. BUT! The tendency of tds in an aquarium is to rise over time. The simple act of adding tapwater to make up for evaporation adds to the tds. Water changes are the best way to counter this, performed at least weekly. Even then, measuring the tds of your tap and the tds of your tank could prove eye opening.

[Vanda lover]

Originally Posted by soobie

I use straight fish tank water all the time, and I grow my orchids (and other house plants) inside. No bad smell, ever. If the tank is well maintained, it won't stink.

Me too. I agree with you. No Smell.