If fertilizing with water taken from an aquarium (with concentrations of amonia, nitrite and natrate, as well as some co2), how often should I add this water to the bonsai for fertilizing?
Thankis in advance!

It is impossible to answer without knowing how much of each nutrient is in there.

I use koi pond water at every watering and for every plant/crop/tree. Values is:

No3 10-20 ppm
No2 0
Nh3 0
Po4 0-1
Kh 8-10
Gh 2-3

I do add extra fertilizer during the summer.

I cant tell about the trees. But the fish dont like no2 and nh3. If you have measurable levels you need better maintenance/ filter.

I never thought about using water from the fish tank for this purpose. Mind is a bit blown at the moment lol

I know it can be used for garden plants in general (and I've been doing it with vegs, w/o any problems), but I've never tried it with bonsai. Like, it will be the same as tap water with an increase in the concentrations of ammonia, nitrite, nitrate and phosphorous. I believe how much of an increase depends on the stocking, maintenance and feeding schedule of your tank. So I wonder if anyone knows a way to get the chemical composition of water?

Send it to an lab for analysis. Some of the more fancy pond stores might do testing too.

I have well water, and will often supplement my fertilizer with water from our koi pond... I may be adding some salt this spring, as I want to get a couple of new fish, so, if I do that, I will not be using the pond water to water my plants... except for the weeds that grow in the stone garden portions of my garden..

Good point! If you are using salt or medecines in your aquarium, dont use that water.

I have never understood the use of salt in freshwater aquarium. I know people do use it from time to time. It is like using weed to cure headache, it solves the problem in the short run, but is really hard to quit. 37 years in the hobby and 5 years as a profession.

The sheap dropping tests found in aquarium stores is Good enough for routine testing of the water. No need for professional analyses before watering your trees.

Tropfrog wrote:

Good point! If you are using salt or medecines in your aquarium, dont use that water.

I have never understood the use of salt in freshwater aquarium. I know people do use it from time to time. It is like using weed to cure headache, it solves the problem in the short run, but is really hard to quit. 37 years in the hobby and 5 years as a profession.

The sheap dropping tests found in aquarium stores is Good enough for routine testing of the water. No need for professional analyses before watering your trees.

do you mean cheap tests with a "c"?
The japanese use it in koi ponds to reduce pressure on the gills, and protect the fish against nitrite. It is also used when introducing new fish to a population to eliminate some bacteria and parasites... there are different recommended salt concentrations for different purposes.

tubaboy wrote:

Tropfrog wrote:

Good point! If you are using salt or medecines in your aquarium, dont use that water.

I have never understood the use of salt in freshwater aquarium. I know people do use it from time to time. It is like using weed to cure headache, it solves the problem in the short run, but is really hard to quit. 37 years in the hobby and 5 years as a profession.

The sheap dropping tests found in aquarium stores is Good enough for routine testing of the water. No need for professional analyses before watering your trees.

do you mean cheap tests with a "c"?
The japanese use it in koi ponds to reduce pressure on the gills, and protect the fish against nitrite. It is also used when introducing new fish to a population to eliminate some bacteria and parasites... there are different recommended salt concentrations for different purposes.

Yes, i am not native nor fluent in English. Thanks for pointing out misspelling.

Salt or not in koi ponds is not really a discussion for this forum. Some do and some not. If you use salt, dont use the water to your trees.

There probably isn't enough nitrates or nitrites to make much difference. I water the trees with aquarium water but that is more because I wax brought up with extreme "waste not, want not " and hate the idea of pouring all that fish stuff down the drain. My wife rolls her eyes and laughs at me.

Look at fish fertilizer and the water from the tank, then smell them both. The tank water just isn't that concentrated.