Chemistry
Liquid lanthanum chloride for elevated phosphate
PhoX is a lanthanum chloride solution that binds dissolved phosphate into an insoluble floc you can trap with a fine filter sock or remove via protein skimming. Use it when PO₄ is high, then keep levels in range with Nereus GFO.
Simple dosing rule
2.2 ml of PhoX removes about 0.1 ppm phosphate in 100 L of system water.
Scale with this formula:
ml needed = 2.2 × (your litres ÷ 100) × (ppm you want to remove ÷ 0.1)
Examples for a 0.1 ppm drop:
| System volume | PhoX needed |
|---|---|
| 100 L | 2.2 ml |
| 200 L | 4.4 ml |
| 300 L | 6.6 ml |
| 500 L | 11 ml |
Recommended plan: lower ~0.1 ppm over one week
Most reefers do best lowering phosphate slowly. For a 0.1 ppm reduction across 7 days, use the table above as your weekly total, then split it into small daily doses:
Daily dose ≈ weekly total ÷ 7
| System volume | Weekly total (0.1 ppm) | Approx. daily dose |
|---|---|---|
| 100 L | 2.2 ml | ~0.3 ml / day |
| 200 L | 4.4 ml | ~0.6 ml / day |
| 300 L | 6.6 ml | ~0.9 ml / day |
| 500 L | 11 ml | ~1.6 ml / day |
Need a bigger drop (for example 0.2 ppm)? Double the weekly total and still spread it over a week or longer — do not dump it all at once.
Dilute for easier measuring (recommended)
Small daily amounts are easier if you dilute 1:9:
- Mix 10 ml PhoX with 90 ml RODI (makes 100 ml diluted stock).
- With this mix, 10 ml diluted = 1 ml PhoX.
- So for a 100 L tank, the daily
0.3 ml product becomes **3 ml diluted per day**.
Label the bottle and use within a few weeks.
How to dose
- Test phosphate (and alkalinity) before you start.
- Add each day’s dose slowly into a 5–10 micron filter sock, or into / just ahead of the protein skimmer, so the floc is captured.
- Mild cloudiness is normal — that is phosphate binding. The sock or skimmer should clear it.
- Retest after a few days. When you are near your target, stop PhoX and maintain with GFO.
- Watch alkalinity — phosphate binders can use a little alk; top up if needed.
Best practice
- Prefer a ~0.1 ppm weekly change over aggressive single doses.
- Best when PO₄ is clearly elevated; once you are low, switch to GFO for maintenance.
- Never pour the full weekly amount straight into the display tank.
- On acrylic systems, keep dosing inside the sock / skimmer path to avoid film on the panels.
- For aquarium use only. Avoid skin and eye contact. Keep out of reach of children.
PhoX is a controlled knockdown tool — slow, measured doses, then let GFO and good husbandry hold the line.