Tom, what are the possibilities?


Junior Poster
Jul 9, 2007
Hello Tom,

I have been giving allot of thought lately about my WCs performed on a weekly basis. (Planted Discus Tank). I currently use the EI dosing method with much success and was concerned with how much H2o I change out on a weekly basis. I have a 5 yr old and was thinking of starting a hydroponics garden with her to further her education in recycling our natural resources and thought I should try and do something with the amount of H2o I swap out each week.... we started a worm compost bed and have great fun with that. She seems to like the natural sciences (the things that I like :) My questions are: Is it feasible to use the Aquarium water (already treated with ferts from the week) as a weekly water change in my new hydroponics garden?? Would you think that the weekly WCs would suffice the nutrient requirements of the typical veggie garden? Thinking of an ebb and flow system and thought who better to ask than an expert:) I also have dry ferts that I currently use for the aquarium and from all I've read the ferts I'm suppling my tank (soon to be a 135 this weekend) it seems possible to this newb:eek: I currently use your GH booster/potassium nitrate/plantex csm+B/mono potassium phosphate /Press Co2 @40 ppm (by DC) and excel. Sorry for the length of the post all but I'm kinda excited about the possibilities:cool:

Thanks again Tom



Lifetime Charter Member
Lifetime Member
Nov 29, 2006
I usually use some of the water from my water changes to water my bonsai's and other plants on my porch.

They seem to do just fine.

Tom Barr

Staff member
Jan 23, 2005
Yes, using the waste water to irrigate works well.
That's what rice farmers do here in CA.
They send their water off to the next stage to water Walnut, almond orchards etc.

If you are concerned about having more sustainable aquariums, then you should get rid of the discus and high light/CO2 enrichment:cool:

That is, if that is truly your goal.
You cannot have your cake and eat it too as many planted CO2 folks seem to think and adding discus, or a high bioload, makes this just that much more of an issue.

To give an agricultural example:

Adding 10-20X more growth rates by irrigating water and applying large amounts of Nitrogen and PO4 fertilizers, keeping a large herd of dairy cattle on a tiny plot and bring is silage from outside sources and then maybe doign something with the waste from all that.

A non CO2 plant approach is far more in line with the morals and philosophies of a balanced ecosystem approach.

No water changes
Slow but decent growth/appearance of plants
Balanced reasonable fish load for the volume and plant biomass
You might decide to top off just a small amount of ferts
You use far less electric and light
Reduced labor, no toxic test kit reagent use
Fish waste gets well processed and used as plant biomass

The slow growth rates and inability to keep large biomloads are the trade offs.

Some seem okay with all that and like to call thier industrial argicultural, landscaping "natural".
ADA even goes so far to claim everything is based on nature and offers a nice little poem about it to make you feel all warm and furry.

Give me a break.

I do both types of approaches, always have.
But folks seem to know me more for CO2/EI, ferts etc and not testing, which is ironic really.

I still keep CO2 high light systems, the plant cuttings pay for the electric differences, my asethetic goals are different at the moment, I need to irrigate to keep the landlord happy with the landscape(the weekly water changes supply the entire landscape water demand now that I changed out the plants in the yard to low water native users).

So you can figure out methods to suit your goals.
However, do NOT fall for these delusional claims about CO2 enriched systems being all balanced and natural.

Far from it.

Tom Barr