Aquarium water as a viable fertilizer?

[IrishCreamCoffee]

Hey all,

Newbie here making a first posting! I took a biology class this spring and remembered something that might be useful for orchid cultivation. Fish produce nitrous wastes in the form of ammonia which diffuses out into their aquatic environment. People who raise fish in aquariums have to change the water frequently to reduce ammonia build up. Ammonia in high concentrations can kill any fish, but it can be beneficial to plants as a nitrogen source. I have an aquarium at home that undergoes many water changes within a month. Is it possible to use the aquarium water as an orchid fertilizer? I understand that nitrification must occur before plants can utilize the nitrogen source. Do the growing mediums, in which most orchids are cultivated, affect the nitrification process and if so, how? I would like to hear some thoughts from the experts on this matter. Thanx!

[Aniko]

Welcome to the forum!
I'm not biologist, but orchids are grown in soilless mixtures which provide few nutrients, so they need a complex, balanced fertilizer containing beside Nitrogen: Phosphate, Potash and micronutrients.

[Ellen]

There are many different forms of nitrogen-containing compounds, and ammonia is not one that I would recommend for your orchids. On top of that, who knows what sorts of bacteria or other fish-tank organisms you might be putting on your plants? Having said that, it probably wouldn't hurt anything, but why risk it? Just pour the dregs from the dirty fish tank down the drain and use a good, balanced commercial fertilizer on your orchids.

[PhalPal]

In addition to Ellen's comments above, there would be no way of determining the concentration of nitrogen (and whatever else) you are giving your orchid. Orchids are light feeders and for this reason you may actually harm your plant.

[IrishCreamCoffee]

Thanx for comments. Guess my fishies won't being helping after all. They'll be so sad once I break the news to them. ; )

[fred]

welcome to the forum

I hope that you enjoy your stay here with all of us orchidgeeks.

what sort of orchids do you grow ?

[pikevi]

Welcome to the forum,IrishCreamCoffee.

I think you could use the water for plants that grow in soil since the ammonia can bio-degrade in the soil( facilitated by bacteria in the soil, I'd imagine). I assume that no other chemicals are used as water treatment in your aquarium.

From the picture I see you have cold water fish (Ryukins/shubunkin/calico/goldfish) which are notorious for high ammonia build-up, since they excrete a lot. Additionally you probably have the temp set to about 20C (72F) or less for them that does not allow ammonia to escape. I would not recommend the water either for orchids or any other indoor plants.

Just out of curiosity what size tank is it? Do you have a good filter? You mentioned changing water 'many times' per month. That is too many water changes unless you have a small tank and many fish. If you have a 35G tank with about 3 pairs of ryukins and one or two plecos( I see you have them), the water change should not be more than 2 per month with a good filter.

Goodluck.

[Hsteve01]

Welcome!
Aquarium water is excellent to WATER your plants with, but I would still use a good quality balanced fertilizer. Aquarium water does have some nutrients in it, but not enough to promote plant growth

[IrishCreamCoffee]

to Fred: hi Fred! Well, I don't actually know what types of orchids I have. You see, I rescued them from certain doom from this lady who sold orchids. Most of the orchids she sold were in bloom and those that didn't get sold by the time the flowers have fallen off get thrown in a big pile (terrible, no?). I grabbed all that I thought I could care for and bought them for a ridiculous price. They haven't bloomed yet so no clue. I think I have several phals among the ranks, but I don't know what the others might be. I'll post some pictures of them and see if you or any others might be able to ID them. Thanks.

To Pikevi: Thanks for the tips. You seemed versed on the subject of raising ornamental fish. Do you have an aquarium yourself? I have one black moor (pictured), a koi (which will need more room soon), and two plecostomus in a 55G tank. The smallest fish is about the size of my palm. So they dirty up the tank very quickly. I'm very anal and prefer the water to be pristine as possible. I do a 30% water change approximately every week or as needed. Is that too much? Am I stressing my fish? Also, I use a water conditioner agent to rid of the chlorine and other harmful chemicals each time I do the water change.

thanks for the replies

[pikevi]

Hello IrishCreamCoffee,

30 percent water change is fine for any fish. But it is usually not necessary unless you have discus fish which are very sensitive about water quality.

With your size tank and the number of fish(es) in it you don't need to change the water that often. Three things to consider here are the amount of food you are giving the fish (All the food MUST be consumed within 15 mins), frequency of feeding( cold water fish like yours are big eaters,so twice a day is best) and three filter. You may be using a mechanical filter or a biological filter but see that the 'through-put' is 55G every 2 hours( at least). I use e-heim and Fluval external canisters.)

Food in the form of pellets are best for them since you can 'suck' them out if necessary.

My suggestion is continue the partial water change every week and reduced the amount of water changed incrementally every week: like 30%, 25%,20 % and so on. Once a biological balance is acheived in the substrates used in the filter , I am sure your partial water change can be done every 4- 6 weeks.
[It is a huge tank for the number of fishes you have]

If the water does not stay crystal clear during that time , DON'T panic That will only be temporary.As long as you don't get too strong an ammonia smell when you stand close to the 'tank' you should be fine.It takes time to strike the right balance.

IT will take a lot to stress the type of fish you have. Dirty water (skin lesions)and too much food(intestinal impaction) are the main causes of death for any type of 'gold fish'.

BTW, Don't be surprised if your black moor changes colour soon.

And watch out for the plecos. They sometimes attack other slow moving fish

Good luck

[jerrymeola]

I raised and sold fish for years before they became unprofitable.

The amount of ammonia (which breaks down into nitrites) is too low to ever hurt you orchids. Equally it is too weak ever to do much good as a feed. Fish emulsion which is much stronger is a weak 1-1-1 fertilizer.

However, aquarium water has filtered out many of the less desirable elements out of the water. It is about the equivalent of rain water. I use it occasionally if it is near a plant I want to water, but even with 30,000 gallons of fish water a day on my farm, I can not be bothered to use it for the orchids. The particles clog the sprayers.

[pikevi]

Thanks jerrymeola.

I did not know the exact analysis of the water. I ,of course, do tests for various compounds in it with my test kit.

I have never used aquarium water for indoor potted plants but have used it on outdoor plants.

30,000 Gallons!!, wow. With 12 aquariums and less than 1000Gs I was going nuts!