Editing Openai/69461f48-2694-8000-89fd-c584fc058607 (section)

=== Assistant: Perfect — thanks for the details. ===
Perfect — thanks for the details. With cardinal tetras, Java fern, Amazon sword, and corkscrew Vallisneria, no CO₂, and a 15” deep tank, you want moderate, stable light with a strong but not aggressive peak. The Fluval Plant 4.0 is more than powerful enough, so this schedule keeps growth steady and algae in check.

Below is a refined, dialed-in schedule specifically for your setup.

==== 15g • Low-tech • 15” depth • No CO₂ ====

===== Very gentle ramp — easy on fish and fern. =====

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===== Builds PAR gradually for sword & Val. =====

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===== This is the max you want without CO₂ at 15”. =====

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Why this works
* Amazon sword gets enough PAR without melting
* Vallisneria stays compact, not leggy
* Java fern avoids algae on leaf tips
* Cardinals prefer slightly dimmer, warmer light

===== Soft, natural fade that looks great visually. =====

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===== - Lights OFF at 9:00 PM =====
* Optional: Blue at 1–2% only if you enjoy moonlight (not needed for fish or plants)

==== - 🌱 Amazon sword & Val are heavy root feeders → Use root tabs every 6–8 weeks. ====
* 🍃 Java fern prefers lower light zones — keep it shaded by Val if possible.
* 🔄 Weekly 25–30% water changes help prevent algae in low-tech tanks.

==== Tell me: ====
* How long the tank has been running
* Whether you dose liquid fertilizer (and which one)
* Any algae you currently see (green dust, hair, brown, etc.)

I can adjust this schedule exactly to match what you’re seeing in the tank.