EI & Discus

The big issue is drought in Oz, so doing more water changes might not be the best idea, nor keeping large Discus.

ADA also suggest 50% weekly water changes, more if things are not doing well.

EI suggets this also, but this is to keep nutrients in a target range.

You only do 1/4 of this.

Check to see if you are wiling to do this increase, and can do something with the waste water(plants, landscaping etc, the lawn etc).

If not, we can modify things somewhat.

Discus honestly do not care even a little about NO3's.
That's just a fish only parameter that says do a water change due to over feeding and all the waste which starts as NH4, KNO3 dosing is an entire other thing.

CO2 is the parameter that is most likely to cause issues for fish(all fish).
Discus seem fine up to 45ppm using really good measurements and behavior and coloration, feeding etc.

With the lower light you have, you are in good shape.
I'd go maybe 25% 2x a week water change and dose about 1/2 full EI dosing.

Or go 50% once a week.
Whatever is easier for you and gets the job done.

Here's the tank, this guy adds 1/3 cup of KNO3 daily:






My Altum tank:


Regards,
Tom Barr

 

Tim, there is a good artilce here in the article's section of fish an toxicity.

http://www.barrreport.com/articles/3267-no3-nh4-toxicity-test-plants-critters.html

A good review for NO3:

- Google Scholar

In this paper, which you may or may not have access to for the full article, the fish are extremely high, 200ppm or more for N-NO3, so this is about 800 ppm for guppies etc and warm water fish are much less sensitive to NO3 overall. Also, adding salts, lik KCL and other ions reduce the toxicity. So adding GH booster might help some, K+, PO4, etc, higher KH's say in the 2-3 range.

And for NO2, which is pretty bad also and last much longer in the systems:
http://afs.allenpress.com/perlserv/?request=get-pdf&doi=10.1577%2F1548-8659(1986)115%3C183%3ATONTF%3E2.0.CO%3B2&ct=1

Regards,
Tom Barr