Optimal Lighting

Above: A 2Hr A20 non-CO2 tank requires minimal maintenance and remains algae free. APT1 (lean water) + JAZZ-enriched substrate (happy shade plants), and 20 PAR lighting.

Above: The hardscape of a 2Hr A40 Iwagumi remains algae-free with minimal maintenance. The 2Hr Way? APT1 (lean water) + JAZZ-enriched substrate (nourished carpet), and 50 PAR lighting.

We don't target any optimal R,G,B setting, as research shows that plants utilise almost all visible light radiation from 400 to 700nm. However we are precise in tuning light strength- to 50 PAR in this example.

We use PAR (Photosynthetically Active Radiation) because it measures what plants use. Unfortunately neither Watts (a measure of power consumption, not output) nor Lumens ( a measure of 'brightness' as perceived by the human eye ) or Lux (1 Lumen per square meter) provide sufficient precision, especially where aquarium LEDs are concerned. 

Why does it matter?

The 2Hr A40 Iwagumi above would look visually similar at both 40 PAR and 80 PAR, but at 80 PAR (double the amount of energy) we would be fighting a constant battle with Green Dust Algae on the rocks and sand.

The 2Hr A20 non-CO2 tank would look indistinguishable at twice the light level (40 PAR) yet would also suffer from Green Dust Algae on the rocks and glass.

With aquarium LEDs getting stronger and stronger, it is much easier than before to inadvertently have too much light.

How do I measure PAR?

Proper PAR meters such as the ones from Apogee can be expensive, costing ~US$700. Inexpensive household Lux meters measure 'brightness' but unfortunately does not consistently match PAR, especially across LEDs / light sources.

PHOTONE APP?

A easy tool would certainly be helpful, so this well-reviewed app caught our attention. We compared readings on a variety of phones (iPhone 11 to iPhone 15 and Androids- Samsung, Google, Xiaomi) against the PAR meters we use: Apogee's MQ-500 and MQ-510. We used a 70gsm plain paper diffuser per Photone's instructions.

1. The app is surprisingly usable on iPhones. However readings vary considerably across Android models. This is probably expected, as the camera sensors across Android models probably vary considerably more than across iPhone models. So basically we find the app usable on iPhones, but a hit or miss on Android models.
2. Paid profile worth it. As the App uses different light profiles to extrapolate / estimate PAR, buying the 'full spectrum LED' profile meaningfully improved accuracy to within 10 PAR (against aquarium LEDs) Note- we are not affiliated with Photone in any way.

What this means

• If you have an iPhone, this app is a worthwhile (and inexpensive) tool to gauge PAR and tune light-strength.
• It is not a precision tool (we would not use it to fine-tune between 17 PAR and 20 PAR) but it is surprisingly accurate for broader estimates: is this 70 PAR or 100 PAR? Is this 20 PAR or 50 PAR? (when both would appear similar to the human eye).

Use Cases

Note: readings refer to measurements at substrate level. PAR is heavily impacted by distance, so readings are higher nearer the surface / light source.

The emphasis is on 'easy / simple'. Of course you can run tanks at much higher light levels. But is akin to driving a much faster car, with algae in pursuit!