Why This Simple Fix Stopped the Algae Problem (Part 3)

This is Part 3, the final reveal, in our series restoring a neglected, algae-covered freshwater (FW) planted tank. Here's every fix that got this CO2-injected tank back on track.

Fix #1: Lighting

After struggling to calibrate PAR with single and dual light bar setups that left uneven shadowing, we switched to the AQUAEL Ultra Slim Bluetooth LED and finally got even light coverage across the whole layout — a prerequisite for controlling algae anywhere in the tank.

Fix #2: Flow & Gas Exchange

The original outflow pipe was hitting the wood as a hard, concentrated jet, causing long strands of hair algae. Switching to an Aquario Neo lily-style outflow spreads water in a 120° fan instead of a direct stream, creating surface ripple that dramatically improves gas exchange — critical in a CO2 tank, where plant-driven oxygenation alone isn't enough to keep CO2/O2 in equilibrium with the outside air.

Fix #3: Filtration

Upgraded to an OASE Biomaster 350 for more flow and biological media capacity, running Purigen continuously. A surface skimmer was also added to remove the biofilm layer caused by lipids released during photosynthesis.

Fix #4: CO2 Delivery

A clogged ceramic diffuser insert was replaced, restoring proper bubble-per-second CO2 injection.

Fix #5: Targeted Algae Treatment

2Hr Aquarist APT Fix was spot-dosed (never poured in bulk) at 1ml per 10L of water in a 24-hour period, with the filter off during application. Fertilization was paused during active treatment to isolate the root cause, then resumed at a controlled rate once the algae was under control.

The Full Recovery Checklist

1. Check and calibrate your lighting
2. Check and correct your flow and CO2 gas exchange
3. Mechanically remove as much algae as possible — there's no shortcut here
4. Spot-treat with an algaecide conservatively, watching fish and plant response
5. Fertilize consistently in small daily doses once the tank stabilizes

This entire recovery took about a month of patient, incremental changes — not a single overnight fix.

Fighting algae in your own tank? Shop AQUAEL Ultra Slim LED lighting and 2Hr Aquarist APT fertilizers at natureaquariums.com.