Stable parameters
Stable water kit for discus
Everything you need to reach and maintain ideal parameters: low TDS, the right KH, stable pH.
Why parameter stability matters
Discus don't die from a slightly higher or lower pH value — they die from constant fluctuations. A tank with a pH swinging between 6.0 and 7.5 from one day to the next is more dangerous than one with a stable pH at 7.8.
This kit gives you the tools to create a constant environment: the same water, the same parameters, week after week.
Reverse osmosis: when it's worth it
If your tap water has TDS above 350 ppm or KH above 10, a reverse osmosis (RO) system is a useful investment. It lets you build the water exactly how you want, with specific remineralizers.
If your water is already soft (KH 4-6, TDS 200-300), you can go with properly conditioned tap water.
✓ What's included
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Clear steps: from box to your first discus
- 1Test your tap water: pH, KH, GH, TDS. Record the initial values.
- 2Decide: RO mandatory if TDS > 350 or KH > 10; optional if the values are already soft.
- 3Install the RO system somewhere with easy access to cold water and a drain.
- 4Set up the pre-mix container (50–100L) with a recirculation pump for homogenization.
- 5Remineralize the RO water with Seachem Equilibrium up to the target TDS (100–200 ppm display).
- 6Record the final values (pH, KH, GH, TDS) before transferring into the tank — they must be stable.
Common mistakes to avoid
- Pure RO water (TDS 0) used directly — without minerals, the pH swings unpredictably.
- Remineralizing with table salt instead of specialized products — discus need Ca, Mg, K.
- Switching abruptly from hard tap to mineralized RO — discus get shocked; transition slowly.
- No pre-mix — water added straight to the tank without homogenization doesn't have the right parameters.
- Uncalibrated TDS meter — it gives you false values and you miss the target by 50–100 ppm.
- Chasing the exact value, not stability — discus prefer a stable pH 7.8 over an oscillating 6.5.
Frequently asked questions
Do I have to use reverse osmosis for discus?
Not necessarily. It depends on your tap water. If the TDS is above 350-400 ppm or KH above 10, RO becomes useful. Below those values, well-conditioned tap water works.
What KH is ideal for discus?
For domesticated discus: KH 3–6. For wild ones (Heckel, Altum): KH 1–3. Stability matters more than the exact value.