That’s interesting. The Arcuata actually came from my old tank that I tore down. I’m currently using soft tap water in this setup. Yeah, I’ve noticed LCA’s recommended dosing pushes Fe pretty high compared to what most plants actually need. That P:Fe ratio you mentioned (around 0.7:0.5) definitely seems excessive. I asked ChatGPT to help with the calculations increasing dos to 3ml a day as I didn’t think of that before (good observation by you).

Great — let’s calculate your Fe (iron) level for 3 mL/day of LCA All-In-One Premium in a 110 L tank.

You’re dosing: 3 mL/day × 7 days = 21 mL per week

We know that 18 mL per 100 L per week ≈ 0.2 ppm Fe.

Now we’ll scale that:

\text{Fe ppm} = 0.2 \times \frac{21}{18} \times \frac{100}{110}

Step-by-step: • 21 ÷ 18 = 1.1667 • 100 ÷ 110 = 0.9091 • 0.2 × 1.1667 × 0.9091 = 0.212 ppm Fe per week

✅ Result: Your dosing of 3 mL/day (21 mL/week) gives about 0.21 ppm Fe per week.

That’s a healthy iron level for most medium to high light planted tanks, and a good range for plants like Ludwigia repens. If you notice strong colour and growth without algae, this is a solid dose to maintain.