Discus Water Testing Experiment.

By: Kevin | April 13, 2011

Hello everyone and welcome to my first blog!

I decided to start blogging about my fish tanks after posting some updates on facebook and talking with friends, most of which appear interested or at the very lease humor me and listen. So what the heck I’ll give this a go.

Quick history: I grew up with fish tanks and have had them around nearly all my life. Tank sizes have ranged from 20 Longs all the way to 150 gallons. 🙂 I have to credit my father, Mark, who got my going in the aquarium hobby. It was a nice father-son bonding experience I hope to share with a son or daughter myself someday.  Mark, Daddio as I like call him, and I have always had African Cichlids. Very beautiful freshwater fish. I’m not going to get to much into them as my current mission is South American Discus Cichlids.

Take a look at these bad jacksons!!


I scored four (2 Males; 2 Females) discus for FREE from a guy in Spencer, IA. These are two breading pairs that I’m attempting to get them to do just that.  My ultimate goal is to have these bread and sell off the babies. A 1-3” baby would easily cost you $30-$60/piece bones at your local pet store. That’s IF they even have them.

Now that I have you up to speed a bit let me get to what I’m currently up to.

Discus like their water uniquely different from most other freshwater fish.
They like water conditions to be:

  1. 82-88 degrees F
  2. pH more acidic; 5.5-6.5
  3. dKh (water hardness or carbonate hardness) 5-10 dKh
  4. TDS (Total dissolved solids; i.e. copper, iron, ect) at 0 TDS
  5. And like all other aquariums:
    • 0 ppm Ammonia
    • 0 Nitrates
    • 0 Nitrites

Most people just throw tap water right into their tanks and make sure the temp is right. This works for most ‘junk’ fish that don’t take much to live. I have come to the conclusion that the more beautiful the fish (fresh or salt), the more water parameters their is to pay attention to. This is partially what attracted me to discus. A new challenge. I’ll admit I have been struggling to get my water conditions correct. The closer I can get them to the natural habitat the more likely they will bread for me.


Now lets talk water.

I, like you, thought all water for your aquarium is created equal. Well,… I was wrong. There is sooo much more to it than you think. For many years Daddio and I would just use tap water and add some water conditioner to detoxify TDS, ammonia, and ect. I’m starting a saltwater tank which has really opened my eyes to different water options.

There is Tap water, RO (reverse osmoses) water, and distilled water. Tonight I took the liberty of testing RO, Tap, and Culligan distilled water.

I used Aquarium Pharmaceuticals, Inc or API freshwater master kit for all tests.

My Results as pertains to my Discus tank.

1st place – RO water. Reading were perfect for discus liking. pH 6.0, Ammonia 0 ppm, Nitrates 0 ppm, and Nitrites 0 ppm and 0 TDS. Everything I’m looking for.

2nd place – Culligan distilled water reading pH 6.6, Ammonia 0.25 ppm, Nitrates 5 ppm, and Nitrites 0 ppm. I don’t know for sure what TDS is but I’m thinkin between 0-50.



3rd place tap water reading an  undesirable 8.2 pH, Ammonia 0.50 ppm,  Nitrates 0 ppm, Nitrites 0 ppm and TDS near 170.


I did two pH tests on tap water. The blue is for testing the low range pH. Once I saw how high it was I had to get out the High pH test kit.

To put all these number into perspective today my tank read 6.0 pH (I used API’s pH down), Ammonia 0.50-1.0 ppm, Nitrates 5 ppm, and Nitrites 0.50 ppm.


Tank tests

So clearly I am going to start using more RO for my discus tank!! 🙂 Well thats enough for now. Hope this helps someone.