hi, new member here. wanted to ask, can i use water from my fish tank( its good for nitrates) to water my wifes bonsai? i use the water to feed my house plants and outdoor plants and they thrive on it.

There are no definite answer to that question.
It pretty much depend on the quality of the aquarium water, what you are adding to the tank and what trees you have.

Water from correctly maintained rift walley tanks is far too hard for many species of trees.
Water from tanks treated with algae poison is not suitable.
Water treated with medicines may be unsuitable.
And the most obvious one: water from reef aquariums is not suitable.

I use the water from my koi pond to water my trees. We have a soft tap water which I treat with sodium bicarbonate and potasium nitrate only. While SB may be bad in huge quantities, my addition scheme pose no threat. PN is just good for the trees but consumed in the bog filter, so not much reach the trees.

cheers. my tank is a cold water tank with zebra danios. water quality is spot on. it will be getting used on a chinese elm.

yorkyjeff wrote:

cheers. my tank is a cold water tank with zebra danios. water quality is spot on. it will be getting used on a chinese elm.

Sounds good to me.

I have three tanks, a Brita filter, and a large trash can. Water filters from the tap into the trash can and then I pour it into the trash can, watering the trees as necessary. The fish all seem healthy and the trees appear to be fine.

cheers for that, looks like i have a lifetime supply of bonsai food. happy days.

Yes. But If you do like Ian and pour it from trash can to trash can. Your trees will get no "food" and you will just have more and more old aquarium water.:woohoo: :woohoo:

Tropfrog wrote:

Yes. But If you do like Ian and pour it from trash can to trash can. Your trees will get no "food" and you will just have more and more old aquarium water.:woohoo: :woohoo:

Agree.

Tree fertilizer is only there if you put it there. There are probably a lot of nitrogen compounds in the water, from urine, but maybe not usable for the trees. There is a lot of sludge in the water which may be very slight fertilizer.

The trees are right between the fish tanks, I usually get at least 10 gallons out of the big tank, it is pretty far from the outside door, and it is easier to water the trees over a week or so than it would be to drag it over to the door. I do it more out of laziness than scientific design.

ill be getting it straight from source. the tank is next to where the tree lives.

Fresh water fish don't pee in the water. They expell nitrogen in the form of amonia from their gills. I am not sure it techically could be called urine, but I am no scientist eigther.

Anyway, if your aquarium is well cycled and healthy the amonia will be broken down in a process called nitrification where the end product is nitrate. Nitrate is a very good source of nitrogen for plants. If there, as in most tanks is an inbalance between fish production and plant consumption, the nitrate will acumulate over time.

The fish also poops and in the poop there are a lot of phosphate and potasium.

Nitrate, phosphate and potasium is what we call NPK in the plant hobby. Called macro nutritions because it is the nutritions plants consume the most. And what you get out of your tank is the most effecient form. Much like inorganic fertilizer, but without the negative environmental effects of the same.

If your aquarium water is soft and healthy, water from fresh water aquariums is the best fertilizer you can give your trees.

Measuring nitrate and phosphate in the water will not only make you stay on top of maintenance of the aquarium but also give you a sence of how much fertilizer your trees gets.

My pond houses a great amount of plants that consume the fertilizer and heavy airation that make the amonia leave the water into the air. I add chemical fertilizer to restore the nitrogen/phosphate inbalance created by the airation. This helps the plants to consume all phosphate and potassium. My water is almost totally clean from fertilizer because of that and technically no water shanges is necessary. Due to animal care laws I am forced to do water changes anyway. That is my reason for watering the plants with pond water. I just think it is a waste to pour perfectly good water out the drain. Obviously I need to fertilize the trees anyway as most people.