Dialing In Light Roasts on the Fellow Aiden

Light roasts are the most demanding coffees to dial in on the Fellow Aiden. Not because they’re complicated—the underlying logic is straightforward—but because the margin for error is narrow. Get it right and you have a transcendent cup. Get it slightly wrong and you get something sour, thin, or both.

This guide covers the specific challenges of light roasts on batch brewers, the pulse-stepping strategy that works best on the Aiden, and the feedback loop that will get you dialed in within three brews.

Why Light Roasts Are Harder to Dial In

Light roasts have three physical properties that complicate extraction:

Higher density. Light roast beans are denser than dark roast beans because they haven’t been broken down by high roasting temperatures. Denser beans require more energy (higher temperature, longer contact time) to extract soluble compounds from the core.

Lower solubility. The compounds that create the bright, acidic, complex character of light roasts are less soluble than the bitter compounds that dominate dark roasts. You need to work harder to extract the good stuff—but if you push too hard, you blow past the fruity and floral notes and land in bitter, astringent territory.

Higher acidity. Light roasts have more organic acids than dark roasts. This acidity is desirable when extraction is in balance, but unextracted light roasts read as harsh and sour rather than bright and pleasant. The line between “vibrant acidity” and “underextracted sourness” is about 0.5% extraction yield.

These three properties mean light roasts require:

Higher brew temperatures (to overcome density and solubility barriers)
More precise temperature control (because the extraction window is narrow)
A strategy that builds extraction gradually rather than front-loading it

Pulse-Stepping Strategy for Light Roasts

The standard Aiden SS (step-and-soak) mode works well for light roasts, but the temperature progression matters more than it does for darker coffees.

The principle: Start lower than your target final temperature and step up through the brew. This gives the denser light roast grounds time to absorb water and heat before hitting peak extraction temperature.

Starting Settings for Light Roasts

Use the Aiden Profile Generator with roast level set to “Light” for a calculated starting point. The generator will typically produce something in this range:

Bloom temperature: 196–200°F
Bloom duration: 40–50 seconds
SS Pulse 1: 200–202°F
SS Pulse 2: 202–204°F
SS Pulse 3: 203–205°F (if 3-pulse profile)

The step-up pattern (each pulse slightly warmer than the last) is intentional. The first pulse is still encountering cold grounds that will absorb heat; the later pulses hit fully saturated grounds at brewing temperature.

Ratio for Light Roasts

Light roasts typically benefit from a slightly tighter ratio than the default. A 1:15 to 1:15.5 ratio (coffee to water) extracts the required compounds without diluting them. The lower water volume also means higher TDS in the final cup, which helps the delicate light roast character register on the palate.

Start at 1:15.5 and adjust based on strength preference after nailing the flavor balance.

Sample Profiles by Freshness

Light roasts are particularly sensitive to bag age because CO2 content affects bloom behavior, and underripe extraction (too little CO2 evacuation before the main brew) is more damaging for light roasts than for darker coffees. These profiles show how settings should shift as the bag ages.

Light Roast — 7 Days Off Roast

Fresh light roasts degas aggressively. A dome forms within seconds and you need the full bloom window to let it subside before the main brew begins. If you shorten bloom at this stage, the CO2 shield causes uneven extraction—bright and flat coexisting in the same cup.

Bean:      Ethiopia Yirgacheffe (Light, Washed, 7 days)
Dose:      40g  |  Yield: 600g  |  Ratio: 1:15
─────────────────────────────────────────────
Bloom:     196°F × 50 seconds
SS Pulse 1: 200°F
SS Pulse 2: 202°F
SS Pulse 3: 203°F

Tasting notes: jasmine, lemon curd, peach. The long bloom at 196°F prevents early over-extraction of the fermentation-adjacent compounds that give Yirgacheffe its floral character.

Light Roast — 14 Days Off Roast (Peak Window)

Two weeks off roast is the sweet spot for most light roasts. CO2 has settled enough that you don’t need to extend bloom, but freshness is still high. This is the profile you want to lock in—brew it now while the coffee is at its best.

Bean:      Ethiopia Yirgacheffe (Light, Washed, 14 days)
Dose:      40g  |  Yield: 600g  |  Ratio: 1:15
─────────────────────────────────────────────
Bloom:     197°F × 44 seconds
SS Pulse 1: 201°F
SS Pulse 2: 203°F
SS Pulse 3: 204°F

Tasting notes: citrus blossom, bergamot, stone fruit sweetness. The 1°F increase in bloom temp and 6-second reduction in bloom duration reflect the lower CO2 content compared to the 7-day profile.

Light Roast — 28 Days Off Roast

Past the peak window, light roasts need more temperature to compensate for the loss of CO2-assisted extraction. Bloom time can be trimmed further; the main brew temperatures need to climb slightly.

Bean:      Ethiopia Yirgacheffe (Light, Washed, 28 days)
Dose:      40g  |  Yield: 600g  |  Ratio: 1:15
─────────────────────────────────────────────
Bloom:     199°F × 38 seconds
SS Pulse 1: 202°F
SS Pulse 2: 204°F
SS Pulse 3: 205°F

The cup at this age has less aromatic complexity but can still be excellent with the right settings. If you notice flatness that doesn’t respond to temperature increases, the coffee has passed its useful window.

The Feedback Loop

Light roasts fail in predictable ways. Here’s how to read the cup and respond:

Signs of Underextraction

Sour, tart, or citric sharpness that isn’t pleasant
Thin body with little aftertaste
Flat or muted aromatics
Cup improves significantly as it cools (a warm cup masks underextraction)

Response: Raise the SS pulse temperatures by 1–2°F. Do not change the bloom. If sourness persists after two temperature increases, extend bloom duration by 5 seconds.

Signs of Overextraction

Bitter, dry, or astringent finish
Heavy body that feels chalky or grippy
Aromatics that smell good but cup tastes harsh
Cup gets worse as it cools

Response: Lower the final SS pulse temperature by 1–2°F. Work backwards through the pulses if needed. For light roasts, overextraction is almost always happening in the final pulse, not early in the brew.

Signs of Correct Extraction

Brightness that tastes pleasant and fades cleanly (not sharp or sour)
Body that supports the acidity rather than disappearing
Aftertaste that’s clean and finishes sweet or floral
Cup is good both hot and as it cools to 150°F

Temperature Reference for Light Roasts

Days Off Roast	Bloom Temp	Pulse 1	Pulse 2	Pulse 3
3–7 days	196°F	200°F	202°F	203°F
7–14 days	197°F	201°F	203°F	204°F
14–21 days	198°F	202°F	204°F	205°F
21–30 days	199°F	202°F	204°F	205°F
30+ days	200°F	203°F	205°F	206°F

Fresh light roasts need lower temperatures because CO2 off-gassing creates turbulence that aids extraction. As the coffee ages and CO2 depletes, you need higher temperatures to compensate.

Common Mistakes with Light Roasts

Treating them like pour-over. The Aiden’s immersion-adjacent brew process extracts light roasts differently than a V60. Pour-over temperatures for light roasts (often 205°F+) are too high for the Aiden’s longer contact time. Start lower than you think.

Dialing in by taste alone on the first brew. Always note the appearance: a well-extracted light roast should have good browning on the spent grounds and no dry spots. Dry spots indicate channeling, which means even your bloom isn’t working correctly. Fix saturation before fixing flavor.

Giving up after one bad brew. Light roast dial-in typically takes 2–3 brews. The feedback loop above is designed to converge on a good profile in three attempts, but only if you change one variable at a time. Change two variables between brews and you lose the ability to know what worked.

Using the same settings for all light roasts. A washed Ethiopian and a natural Colombian both qualify as “light roast” but need very different settings. Process type matters almost as much as roast level for light coffees. If you’re brewing a natural light roast, start with the natural process guide first, then apply the light-roast temperature logic on top.

Community Profiles for Light Roasts

Browse community profiles and filter by Roast: Light. Pay particular attention to the bloom settings and the number of SS pulses—light roast profiles in the community library tend to have longer bloom times and more pulses than medium/dark profiles. This reflects the real-world finding that light roasts benefit from a more gradual, stepped extraction approach.

When you find a profile for a coffee from the same region and roaster as yours, use its bloom duration and pulse temperatures as a cross-check against your own settings. If your bloom is running 10 seconds shorter than successful community profiles for similar coffees, that’s a signal to extend it before adjusting anything else.