Backyard Aquaponics
A place to discuss aquaponics

I was wondering if you can safely eat vegetables grown in aquarium water. I asked at the local college but they did not know the answer. My aquarium is about 10 years old, and the fish seem to be fairly healthy. I have had a houseplant growing in the river tank for about 5 years.

I just joined as a new member of this website. I have been searching the internet for many days when I ran across this web site. I didn't know that "Aquaponics" was the term that I was looking for, but I am glad that other people have done this before.

I have an aquarium with about a half-dozen tropical (fresh-water) fish living in it, including tetras, siamese algae eater, and a pleco. I am also growing a house plant in it, which is "rooted" in the gravel in upper part of the 20 gallon fish tank. The aquarium is a modified "river tank" design, which recirculates the water through a charcoal filter, and also uses the roots of the plants to do some of the filtering of the fish waste.

My question is: If I decide to grow lettuce or basil, etc. in the tank, will I be able to safely eat them? My concern is that there may be some unhealthy bacteria, virus, waste products, etc. in the fish water. Is there a listing of all the things that could be harmfull to growing vegetables in your aquarium, such as chemicals, silicone, filter, plastics, etc that may cause the lettuce to be non-edible?

Thank you,
Jonathan

Hi Jonathon,
Short answer: You would be doing what we are all already doing. Eat it! OK, rinse it lightly in tap water, then eat it!

Although I personally wouldn't drink my tank water without boiling it, I don't feel that the bacteria we have in the filtration is generally harmful. If the silicone were going to be harmful to you, it already would have killed the fish.

Caveats:
- If you have been treating fish disease with medications (other than salt), I would not eat the veggies. The nasty chemicals can be absorbed by the plants (as well as the fish), and some of them scare me. Do several water changes to purge the system of medications before you plant edibles. Same problem with odd heavy metal objects, or lead weights on your aquatic plants. Get rid of them and do water changes.

- If you have a suppressed/compromised immune system, cook your veggies first. (You were doing that anyway, right? And the fruit. And no sushi, right?)

Welcome! This site is filled with good info. Take some time and read the old posts. There's a wealth of stuff in here.

Janet,

Thanks for the quick response. I had never thought of toxic lead weights and medicines for sick fishes. That's the kind of information that I was looking for! The vegetables that I want to grow in the aquarium (such as lettuce, basil, etc.) will be eaten raw; and lettuce contains lots of water. I really want to feel confident that I have removed all hazardous substances from the tank before I eat the vegetables and herbs.

Has anyone ever made a listing of all the materials that are commonly found in aquariums that could be hazardous? This would be a good list to post on the forum, and would be great information for beginners such as myself.

For example, how is this for starters...

LIST OF HAZARDOUS MATERIALS TO AVOID IN YOUR AQUAPONIC TANK:
1. Lead weights (frequently used to keep aquarium plants on the bottom)
2. Silicone caulking that is non-aquarium rated (i.e. with arsenic preservatives)
3. Fish medications
4. etc. ?

Thanks,
- Jonathan

Welcome to the site!
The plants work as a filter. People have been using manure for eons as a fertilizer, if fish poo were a really bad thing, the human race would have died out long ago.

Listen to Janet- she has summed up the caveats.

The tank water is probably cleaner and more chemical free than tap water, the only thing that may be a problem is biologically active cultures (bacteria, etc.) These are probably not as bad as water our forefathers have drunk for millenia, but our systems are not accustomed to filtering out biological organisms, so _IF_ you wanted to drink your aquarium water, I would boil it or innoculate it with food grade peroxide.

btw, we did have some spirited debates a while back about whether certain members should ... uhm... introduce human bodily wastes into their system to kick-start the nitrogen cycle, and how safe it would be to drink the water. My concern about the first one was that e. coli or other human pathogens could be introduced. Another member did offer that he blamed a recent illness on an overly vigorous cleaning of his system. My overall take is that you should treat aquarium water with the same respect that you would your garden soil. Don't eat dirt, wash your veggies, wash your hands, and don't pee or poop on the basil.

The list is pretty good. Just remember that what you put in has to come out via water changes, evaporation, vegetable matter, or fish matter.
If you are planning to eat the fish, I think you have more concerns with toxic buildup than in the plants.

With the plants, a couple water changes should dilute any toxic substance (that isn't being re-introduced into the tank) to an "acceptable"level.

Greenedo -- don't laugh, but my water comes out of the tap with nitrates of 20!!! Hmmmm. In that respect, my tank is cleaner than my tap water at times.

Jonathan,
It would be difficult to list -everything- hazardous, and know that you got it all. Your list is a good start. In general, you want to use fairly inert things (like glass or non-coated, non-metallic gravel), or things rated as food grade (like certain plastics, but not others). Another clue that it might be ok to use is if it already comes in contact with your food supply (like brass fittings in plumbing, except that it apparently doesn't handle ammonia well. However, an established system won't have ammonia in measureable amounts). Sometimes something is probably safe enough and there're not a lot of alternatives anyway (like PVC piping). Or it doesn't come in contact with human food, but it's used with animals (like Rubbermaid stock tanks). Just give careful thought to anything that could be in the tank or in the water. You'll be fine.

Human urine is generally sterile.

njh, true. However, it is not if you have various infections, and those germs are not what we want to introduce to the aquarium. The human private parts are also not sterile. This is why when you are collecting a specimen for medical testing, they ask you to catch it mid-stream. That allows the urine to rinse surface contaminants away.

'Bottom' line: you may not pee in my AP system.

Or Mine LOL

However, the stuff that lives on humans a) probably does not interact with fish or plants and b) does not get there from food we eat. So using human urine probably does not form a parasite loop.

I spose you could UV sterlise it first (leave it outside for a day .

Personally I put mine on the lemon tree...

njh, I was more concerned with fecal cross-contamination of the urine, and subsequent re-contamination of humans. I was not concerned with what it would do to the aquarium. Perhaps I am more cautious than most because a) I have children and b)my husband actually IS immuno-suppressed (transplant patient). You may call me a prude if you wish. You still may not pee or poop in my AP system or my dirt garden.

http://conference2005.ecosan.org/presen ... onning.pdf
http://www.drgreene.org/body.cfm?xyzpdq ... l&ref=1088

Jonathan, don't let us scare you away. Anything else you need to know about what -not- to put in your aquarium? I promise to get off my soapbox (again) about introducing human waste into a foodstream.

janet: pity. You're throwing away your best and cheapest source of nutrients. The mexicans recycled everything in an AP system for a thousand years, and what killed them was smallpox, which is not water bourne...

(Having said that, I'm not peeing in my ool either.

Man I just love some of the stuff that comes up on this forum! It's great!

Some people I know are composting their dog poop in a normal worm composter. They're not applying the subsequent liquid to anything they'd eat (nothing leafy, or small) but are watering their fruit trees & other trees with it. I'm still not sure about that, but *shrug* it's better than chucking it in the bin or leaving it outside somewhere.

purrsikat: I'd worry that when I wormed the dog my worms would die?