So I have this 30-gallon aquarium.
And this aquarium has 9 cichlids.
And the cichlids have 2-3 meals per day.
And the meals they have come out as fish poop.
And this fish poop has nitrates.
And the bacteria in the aquarium turn some of the nitrates to nitrites.
And I clean the aquarium twice a week by vacuuming the bottom (approx 5 gallons of water is exchanged).
I have to do something with the “dirty” water. Seems fitting to put it on my flower gardens and by my trees and shrubs, what with nitrates and nitrites being good for plant growth and all.
However, I hesitate to put it on my vegetable garden, since it’s not “composted”. Not that I know what “composted” means, or how to do it with fish poop anyway. I’m kinda new to this gardening thing. I just heard that uncomposted manure is a very bad thing on vegetables for people who want to stay healthy.
My question is this:
If I were to pour my aquarium water on my vegetable garden plot now, during the winter when nothing is growing, and stop before planting season, will I be relatively safe?
My parents have had aquariums on and off for the past 30 years, and my mom puts the water in houseplants! Hasn’t killed any yet- on the contrary, they’re really lush and crazy green when they have an aquarium.
Normal poop is pretty bad for plants uncomposted because it’s concentrated- the plants get too much nitrogen and get burned. Luckily, aquarium water is pretty dilute(how much poop is actually in 5 gallons, anyway?) so it’s fine- kind of like natural Miracle-Gro, I imagine.
I’d think you could pour it on during the growing season and be safe, especially outside. But yeah, you’ll be just fine doing it now during the winter!
When I lived back home I had several 35g tanks setup. I always gave the removed water to my mom for the plants. No idea if it actually made any difference; it didn’t seem to cause any problems.
Within the fish keeping community I’ve heard its a generally accepted practice.
I’d estimate about 3 tablespoons, based on what I see when it settles. Plus, I understand, the water itself has the nitrates in it.
Also a correction to my original post: The bacteria cycle in the aquarium is that the fish produce ammonia which becomes nitrites which become nitrates.
If you have a compost heap, I’d recommend adding it to that; two of the most common reasons for slow decomposition in compost heaps/bins are lack of moisture and lack of nitrates.
I used to pee into my compost bin to give the bacteria a boost, particularly in the days when I was doing a lot of carpentry and my wood shavings were going in there.
It’s not heavy thick matter, and would be broken down really fast. Like finely cut grass that acts like a brief mulch in a lawn before composting and feeding the soil, any small matter like you have can be used without much concern for ‘composting’ it.
Old tank water is the best thing for plants. Water with it, and you will notice a difference. Plants love the nitrates. In fact, I believe you can set up a planted tank with a few fish and basically create a symbiotic relationship that doesn’t require a whole lot of extra upkeep. (Plants produce oxygen for the fish, fish produce ammonia, bacteria turns ammonia into nitrites and then nitrites into nitrates. Plants are fertilized by nitrates. And the circle of life begins again.)
You’ll be completly safe doing this at any time of year. Fish waste in normal aquarium water is so dilute it can’t burn plant roots. It is already on it’s way to being composted by the bacteria in the water and substrate.
Part of my job is researching aquaponics, which is running a hydroponic vegetable operation with water from big fish tanks. The fish waste provides the majority of the nutrients for the vegetables rather than adding them chemically… although there are usually still a few minor additions that need to be made. The plants will grow quite happily in completely raw fish sewage… you can eat the fruits right off the plants growing in it - it won’t hurt you.
Thing is you need a good amount of feed going in to the fish before there’re enough nutrients to really make it work. In a 30 gallon tank with 9 little fish which has 15% of it’s volume replaced weekly, there won’t be enough nutrients in the water to make an appreciable difference to normal plants in of themselves… especially when you apply that water to an entire garden.
This water would be better than say tap water though, and you might see a noticable difference from a combination of things the fish water would contribute (different pH, decreased chloramine concentration, different ion ratios…). But the nutrient levels in the water you have will be pretty low due to a small tank, low stocking rate (= little food going in and a small volume of water coming out), and the frequency with which you change the water - it’s too clean to grow giant mutant man-eating tomatoes :D.
Good to hear that it’s not a problem. With all this recent press around the hepatitis outbreak in Pittsburgh (supposedly linked to green onions grown in uncomposted sewage) I was getting a little nervous.