Compatibility Checker.
Tank-Mix Compatibility Checker
Will these two compounds tank-mix safely? Quick lookup against known incompatibilities.
How tank-mix compatibility works
Two compounds dissolved together in solution may react with each other before reaching the plant. The most common consequence is precipitation — insoluble salts form, drop out of solution, clog drip lines, plug emitters, and rob the plant of nutrients you paid for. Less commonly, chemical reactions release gases, change pH dramatically, or break down active ingredients.
Most incompatibilities are concentration-dependent. Calcium and sulfate are happy together at recipe-final concentration (60-200 ppm Ca, 50-200 ppm S in the final solution) but precipitate as calcium sulfate (gypsum) when you mix concentrated stocks (1000+ ppm of each). The rule of thumb: safe in final solution; check carefully in stock.
The classic two-tank split
Hydroponic recipes are typically split into Tank A and Tank B to avoid the calcium-phosphate precipitation:
| Tank | Holds | Why |
|---|---|---|
| Tank A | Calcium nitrate, calcium chloride, iron chelates, micronutrient chelates (Mn, Zn, Cu, B, Mo) | Ca-bearing compounds isolated from PO₄ and concentrated SO₄ |
| Tank B | Potassium nitrate, monopotassium phosphate (MKP), magnesium sulfate, potassium sulfate, ammonium nitrate, ammonium sulfate | Phosphate and sulfate compounds; no Ca |
| Tank C (optional) | pH down acid (phosphoric, nitric, citric) | Strong acids isolated until injection point |
When making final solution, fill irrigation tank with water to ~80% volume, add Tank A at recipe rate, agitate 60 seconds, add Tank B at recipe rate, agitate again, test pH, adjust with Tank C, top off to volume, deliver. The dilute final mix is stable.
Why this matters in practice
If you mix the wrong things in concentrated stock, you'll see:
- White or beige sediment at the bottom of the tank
- Clogged drip emitters or fertigation injectors
- Cloudy stock solution (vs. clear)
- Lower-than-expected EC (because some of your nutrients precipitated out)
- Inconsistent results between feedings (depending on whether you got the precipitate or the supernatant)
This is one of the most preventable causes of "my plants aren't responding to the recipe" frustration. The chemistry is well-understood; the trap is a beginner's mistake but easy to avoid.
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