Full Member
Posts: 10
Joined: Wed Mar 07, 2007 5:27 pm
Location: Edmonton, Alberta, Zone 3

Recycling Fishtank Water as Fertlizer

I have two 10 gallon fishtanks (well, one's a salamander tank, only about 2-3 gallons of water in it) that, of course, have to have the water changed regularily. My tanks are as close to natural ecosystem as I could get it; I use very few chemicals, relying on a good bacteria colony for Ammonia breakdown instead.

Last year was my first year gardening and I decided to conserve water by using the water I change out of the tanks to water and fertilize my garden. I don't know if this is actually a good idea or not, but the results were pretty good! I used this water about 90% of the time (when it got too warm over a short period of time I had to resort to the hose) and only added other fertlizer to do my tomatoes now and then. The only other thing to be careful of was to make sure I washed by 'edibles' before consumption which I would do from the store anyway.

Again, I don't know if this is normally recommended but it worked great for me and helped keep my water consumption down and my garden looking great (expecially for a newbie)!


Greener Thumb
Posts: 1868
Joined: Wed May 26, 2004 2:44 am
Location: Maryland zone 7

I used to use the fish tank water to water my houseplants. I did find this site about the potential for releasing invasive plants into the environment as a potential problem.


Full Member
Posts: 53
Joined: Tue Apr 24, 2007 10:51 pm
Location: Scottish Borders

Souds pretty good to me especially if it is relatively chemical free. What about using the water to keep a compost heap moist every now and then? Then you could use that on your pots or beds. I think maybe the only concern is what is contained in the water from your tanks is then exposed to the environment.
Your local pet or garden store could probably advise.


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