Better Your Brew Series || Volume II Ch. 1 of 3 || Core Brewing Variables: What You Can Control

Volume I focused on gear and advanced techniques for improving your brewing. In Volume II, we'll explore the variables you can actually manipulate to dial in your favorite cup. This first chapter begins by identifying the core variables within your control and explaining how each one impacts your brew. The next chapter explores troubleshooting your brew using these variables and even gadgets that we discussed earlier. And in the final chapter, we will explore some controversial topics and myths in coffee.

CORE BREWING VARIABLES || Chapter 1. What You Can Control

Obviously you can choose various brewers, filters, and other tools to influence your brew. However, we already explored that in detail in the last few posts. You can also choose specific coffee to start with, based on origin and processing method, but we will get to that later in the series. For now, we will focus on what variables you can manipulate each time you brew, once you have chosen your coffee and all of your equipment.

Dose

Some people may confuse dose with brew ratio, but dose is just one part of it—the coffee part. The amount of coffee you put into your brewer can significantly affect your final cup. Dose impacts several aspects of your brew: flow rate, extraction, strength, channeling, and balance.

When you increase your dose, the first thing to consider is how it affects all the other brewing variables. Just adding more (or less) coffee rarely improves your cup on its own. If you change the dose, you should also consider adjusting your brew ratio, water temperature, grind size, and more. In fact, changing any brewing variable will often require you to revisit others you may have already dialed in. These variables are interconnected—they don't work in isolation when it comes to shaping the final flavor of your coffee.

In general, if you increase your dose, you'll want to consider changing your brew ratio—unless you're intentionally trying to adjust strength. You may also want to lower your water temperature and reduce agitation, because a larger dose increases the contact time between coffee and water, which in turn increases extraction.

While more extraction might sound like a good thing, it can lead to bitterness and astringency if pushed too far. Trying to make a stronger cup simply by using more coffee—without changing anything else—can easily lead to over-extraction and unpleasant flavors.

One major way dose affects your final cup is through flow rate. This influences how long the water is in contact with the grounds and how efficiently it extracts what you want (and don’t want) from the coffee. Changing your dose also changes the coffee bed depth—the thickness of the layer the water must pass through—and the resistance that bed offers. The deeper the bed, the more resistance, and the more opportunity for channeling, where water finds the path of least resistance, often leaving much of the coffee under-extracted. This could be through small "tunnels" in the coffee bed or through bypass (depending on your brewer design). All of this affects extraction, contact time, and ultimately, flavor.

Your brewer type and size will naturally place limits on the dose you can use. For example, a conical brewer like the Hario V60 creates a deep central coffee bed, while a flat-bed brewer spreads the dose more evenly. So a 20g dose in a conical brewer creates a deeper bed than in a flat-bottom brewer.

This is one reason flat-bed brewers tend to promote more even extraction, while conical brewers may offer more complexity, especially at higher doses. But if you use too much coffee for your brewer size, the water may not reach the bottom layer with enough extraction potential left. Water extracts compounds as it passes through, and eventually becomes saturated—meaning the top layers of your coffee bed may be over-extracted, while the bottom is under-extracted. This can create complexity, but it can also lead to bitterness and imbalance.

Try experimenting with different doses in your favorite brewer to find what you enjoy most. Personally, I really like a 15g dose in a size 02 Hario V60. A 20g dose still tastes good—but not as interesting. At 30g, the coffee is drinkable, but flatter and less dynamic. On the other hand, in the Orea V4 Narrow, I’ve found that 20–25g produces an amazing cup. So: experiment and compare cups—the sweet spot is different for every brewer.

Grind Size

Grinding is one of the most impactful variables when it comes to the flavor in your cup. Particle size, uniformity, distribution, and the amount of fines all significantly influence extraction and the final flavor profile. There are general recommendations for grind size based on your brewing method, but these usually get you a decent cup—not the great one you’re after. You'll often see terms like “fine,” “medium,” or “coarse,” or comparisons to familiar textures like sea salt or flour. These can be helpful for beginners or anyone without tools to measure grind size more precisely.

However, to really dial in your coffee, it’s worth learning how grinds look at different micron levels, and more importantly, getting to know your specific grinder. Just because you and someone else use the same model doesn’t mean your grind settings will produce the same results. Burr alignment, burr type, and wear can vary—even between identical grinders. Plus, your taste preferences are your own.

So don’t set your Comandante C40 to 25 clicks and assume that’s the magic number just because someone on a forum swears by it. If you adjust grind size because it worked for someone else, you might end up chasing the perfect cup by tweaking every other variable—and still missing it.

Grind size in a recipe is a starting point, not a rule. You’ll need to adjust finer or coarser depending on your setup. Even with a burr grinder, a flat burr will produce a different flavor profile than a conical burr. And even if you somehow use the same brewer, filter, coffee, water, and grinder as someone else, you’ll still need to dial in for your own taste.

Also, keep in mind: a grind size that works for one coffee won’t necessarily work for the next. You may need to adjust as the coffee ages, or as ambient temperature and humidity change. Roast level, origin, and processing method will all affect what grind size works best.

It may seem like a lot—and it can be—but with patience, it pays off. I’ve had coffees where, after dozens of brews, I finally hit that perfect grind size. And when it happens, I literally pause to acknowledge how amazing the cup is compared to the 30 before it.

It’s not just the size of the grind that matters—it’s also how consistent the grind is. A high-end grinder will produce particles that are much more uniform in size. Lower-end grinders, on the other hand, produce a wider range of particle sizes, often with a lot of fines (tiny dust-like particles). Fines can clog your filter and lead to over-extraction, causing bitterness or dryness. If you’re using a blade grinder, the issue is even worse: you’ll get a chaotic mix of large, jagged boulders and powdery fines.

Why does this matter? Because as water flows over these particles, it extracts from each one at a different rate. That inconsistency can lead to muddiness or imbalance—cups that are too bitter, sour, or astringent. A good burr grinder helps ensure that each particle has a similar extraction potential, leading to a more balanced, clean cup.

Let’s say you have a decent grinder and can manage fines and boulders—now your job is to find the right grind size. Grind size affects flow rate, extraction potential, and risk of channeling. When you grind coarser, water flows faster through the bed. If other variables (like dose or brew time) stay the same, this reduces contact time and can result in under-extraction—a weak, sour cup lacking sweetness or complexity. When you grind finer, you slow the flow and increase contact time. This allows water to extract more, but also increases the risk of over-extraction and channeling. Channeling happens when a dense coffee bed creates too much resistance, and water finds paths of least resistance—tiny "tunnels" where it flows too quickly. This results in uneven extraction: some grounds are over-extracted, others under.

The ultimate goal is to extract the desirable flavors and stop before the undesirable ones come through. With grind size, this means creating enough contact time—but not so much that you end up with bitterness or dryness.

Grind size is one of the most commonly adjusted variables when dialing in a brew. But remember: adjusting grind alone may not solve everything. Each brewing variable interacts with others, and they each affect your cup in different ways. You might also need to tweak water temperature, agitation, or your pouring technique. Grind size can also be a great way to shift the flavor profile. Grinding finer can bring out more acidity and fruitiness, while grinding coarser can emphasize sweetness and clarity.

Try running comparisons: brew two cups with everything exactly the same except for a small grind adjustment. That kind of focused experimentation will help you develop a better understanding of how grind size shapes the cup—and how to use it to brew better coffee.

Ratio

Ratio refers to how much water you use to extract a given amount of coffee. For example, if you grind 15 grams of coffee and want to aim for a 1:15 ratio, you’ll use 15 grams of water for every 1 gram of coffee — which means pouring 225 grams (or milliliters) of water over your coffee. In coffee, weight is always used for ratio because it provides consistency and precision. I mention milliliters only because, by coincidence, 1 milliliter of water equals 1 gram in weight. The reason we measure by weight has a lot to do with espresso, which produces crema. Crema can add volume when measuring by milliliters, making the results inconsistent. Using weight eliminates this issue, as crema doesn’t affect the scale.

It’s also important to note that the amount of water in a ratio refers to the brewing water, not the amount of liquid that ends up in your cup. For instance, if you use 15 grams of coffee and 225 grams of water, you’ll likely end up with around 185–195 grams of brewed coffee. The rest is absorbed and held by the grounds and filter.

There are general ratio ranges recommended for various brewing methods. These are good starting points, but don’t be afraid to experiment by adjusting tighter or wider depending on your taste. Also, ratios don’t have to be whole numbers — you can absolutely use something like 1:16.4 if it works for you. In fact, the so-called "golden ratio" for pour-over is often cited as 1:16.7, though that’s highly subjective.

Here are some common ranges:

• Espresso: 1:1 to 1:3

• Pour-over: 1:15 to 1:18

• French press: 1:12 to 1:15

  
  

Personally, I’ll sometimes go as wide as 1:19 or 1:20 for pour-over when brewing a Gesha. Ultimately, the right ratio depends on how strong you want your coffee and what type of body and mouthfeel you prefer. If you want a heavier, stronger cup then go with a 1:15 ratio, if you want a lighter and more tea-like cup that may focus on florals, try 1:18 or 1:19. Personally, I will try 1:15-1:16 for washed coffees, 1:17 - 1:19 for Geshas, and 1:16-1:17 for heavily processed coffees. But this is my taste profile, and not a universal guideline.

A tighter ratio means less water for the same amount of coffee — for example, 1:13 instead of 1:17 — and this will result in a stronger-tasting cup with a heavier body. That’s because more coffee solids end up in the final brew, as compared to the amount of water in the cup. But be careful: if your ratio is too tight, your coffee can become bitter, flat, or muddy. You need enough water to extract all the desirable compounds and then balance those flavors in the cup.

On the other hand, if your ratio is too wide, like 1:20, your coffee may taste weak or watery. This can happen when you’ve already extracted all the good stuff, and then simply dilute it with extra water, pulling in undesirable compounds along the way. This is even more pronounced in espresso. For example, a 1:1 shot might taste sour, while a 1:3 shot can lean bitter — so the ratio really matters.

Ratio is a great variable to adjust when dialing in your brew, but it doesn’t exist in a vacuum. You also need to consider grind size and dose. For example, if you’re changing your ratio from 1:17 to 1:18, make sure the dose isn’t too large for your brewer. If it is, and extraction becomes too high, you can reduce the water temperature or agitation to compensate. Another option is to brew a concentrate, such as at a 1:10 ratio, and then add additional water as a bypass afterward. It all depends on the flavor, strength, and mouthfeel you’re aiming for.

All that said, recommended ratios are just to get you in the ballpark. Do whatever tastes good. I pull espresso at 1:4.5 usually, because my tastes prefer it. I have even found that I prefer Turkish style coffee to espresso because to me it is like a 1:8 espresso shot. What matters is what the cup tastes like to you and if you like it. Unless I come over, then brew it how I like it, or I will insult you. You also want to remember that the ratio will vary depending on the origin and processing type of the coffee you are brewing. You may like a washed Gesha at 1:18 and an anaerobic processed Kenya coffee at 1:16. Try different ratios and see what you like, that is the fun of coffee, exploring.

Pour Structure

Pour structure is an important variable in pour-over. You don’t need to worry about this when brewing espresso, obviously, nor is it a concern for immersion-style methods like French press or cupping. Pour structure really only impacts the final cup when using percolation-style brewing, such as pour-over methods. There are a few key areas of focus when it comes to how you structure your pours: the bloom, number of pours, timing, height and flow rate, and your pouring motion. I’ll also touch briefly on hybrid brewers, kettles, and drip-assist tools, as they relate directly to how you control your pour.

The overall goal of pour structure is to manage the saturation and agitation of the coffee grounds, while also maintaining consistency so the process is repeatable. How you pour affects the final cup in many ways, particularly in how the water interacts with and disturbs the coffee bed. One thing that stays relatively constant, though, is the bloom—your first pour should always be the bloom. During this stage, you pour roughly 2 to 3 times the weight of your coffee in water—so for a 20-gram dose, that means about 40 to 60 grams of water—and let it sit for 30 to 60 seconds before you continue pouring. To bloom properly, you want to ensure that all the coffee grounds are saturated quickly and evenly, but without introducing too much agitation. This sets up an even flow of water through the coffee for the rest of the brew and allows for more consistent extraction.

The main purpose of the bloom is to allow carbon dioxide (CO₂) to escape. While CO₂ helps preserve freshness in roasted coffee, it can get in the way during brewing by creating resistance between the water and the coffee grounds. If you skip the bloom or do it poorly, water will struggle to extract the soluble compounds effectively and will do so unevenly. You’ll know CO₂ is being released properly when you see bubbles rising to the surface of the coffee bed during or just after the first pour. How fresh your coffee is, or how recently it was roasted, will determine how long you should bloom. The fresher the coffee the longer the bloom should be to allow adequate time for the CO₂ to dissipate as much as possible.

After the bloom, you’ll need to decide how many pours to use, how much agitation you want to create with each, and what pouring pattern you’ll follow. Once you’ve settled on your brew ratio, you can divide your total water volume however you’d like—either in one continuous pour or multiple pulses. For example, if you’re using 25 grams of coffee and a 1:16 ratio, that’s 400 grams of total water. You might bloom with 50 grams, then do four pours of 87.5 grams each. Or you might pour the remaining 350 grams all at once after the bloom. The choice will affect the final cup. Personally, I will use 4 or 5 pours when I really want to pull out fruity flavors and acidity. I will do 3 pours when I want to round the cup out more with more sweetness and to balance the acidity. My favorite is a hybrid recipe, where I will immerse the bloom, do two pours, then immerse the final pour. This gives me a juicy, bold, well rounded cup.

In general, more pours can lead to higher extraction and will tend to emphasize acidity. Fewer pours—say, two or three—can round out the cup more, focusing on sweetness and body. The timing between your pours also plays a role here. If you let the water drain fully between pours, you increase extraction by constantly introducing fresh water to the grounds. On the other hand, if you wait 20 to 30 seconds between pours and add more water while there’s still some remaining in the brewer, you increase the immersion time, which tends to enhance sweetness and mouthfeel.

No matter how many pours you choose, it’s crucial to saturate the entire coffee bed evenly each time. This can be done with a spiral motion—pouring from the center outward and then back in again—or with other patterns like a figure eight or flower shape. The goal is always even, consistent water distribution to avoid uneven extraction or channeling.

In addition to pour pattern and timing, the height and flow rate of your pour also influence the final result. The height you pour from affects how much agitation you cause and how that agitation behaves. If you pour from too high above the coffee bed, the water can punch through the surface and disrupt the coffee too much, pushing fine particles downward and increasing the risk of clogging. It can also force more fines through the filter, which affects the clarity and texture of your cup. Pouring from too high can also lead to splashing and messy brews.

Flow rate plays a similar role. If you pour too quickly, you may cause over-agitation, which leads to clogging or channeling and reduces brew control. Water may pass through the coffee bed too fast, resulting in under-extraction. Pour too slowly, and you may extend the contact time too much and lose desirable balance—possibly over-extracting unpleasant compounds while under-agitating the slurry. As with most things in coffee brewing, it's about finding the right balance. There is usually an optimal height and flow rate for your particular coffee, grind size, and recipe.

All of this is why a gooseneck kettle is so essential for pour-over brewing. You need precise control over the stream of water in order to manage both saturation and agitation properly. This is where drip-assist attachments can help. If you don’t have a gooseneck kettle, or if your pouring technique still needs work, a drip-assist helps distribute water more evenly over the coffee bed with less effort. I talk more about this in Volume I, Chapter 2, if you want to revisit that section.

You might also want to try using hybrid brewers like the Hario Switch or NextLevel Pulsar. These devices combine percolation and immersion elements, which can help smooth out inconsistencies in your technique and often result in a more rounded final cup. I have a go-to Hario Switch recipe you can try if you're interested.

At the end of the day, your pour structure—including the number of pours, the height and flow rate of your pour, and your pattern and timing—will all directly shape the taste, body, and clarity of your final cup. If you're still practicing or trying to build consistency, using a hybrid brewer or a drip-assist tool can really help improve your results as you dial things in.

Agitation There isn’t too much to dive into here, as we already explored pour structure in the previous section. However, I do want to discuss the pros and cons of agitation, as well as when and how it can be useful. To be clear, agitation is any disturbance to the bed of coffee—whether through pouring, stirring, shaking, or swirling.

Agitating the coffee bed during the bloom is a great way to ensure quick and even saturation of the grounds. This maximizes the water’s ability to extract soluble compounds from the coffee and reduces the likelihood of channeling throughout the brew process. Agitation ultimately increases the extraction of your final cup by ensuring all grounds are evenly saturated, helping release trapped CO₂, and increasing the amount of water passing over each coffee particle—providing more opportunity for extraction. You are essentially adding energy to the coffee slurry, which also helps break up clumps for a more even extraction.

Agitation is especially useful when dialing in a dense coffee, such as a light-roasted, washed Ethiopian. These beans are dense and lightly roasted, making them harder to extract, but they can handle more agitation because they are washed. In contrast, darker roasted beans are more porous, lower-elevation coffees are less dense, and natural or heavily processed coffees can become overwhelming if agitated too much.

The bloom phase is usually the best time to agitate, either by stirring with a spoon or swirling the brewer after your pour. You want to ensure fast and thorough saturation of all grounds during the bloom. For very light, dense beans, consider pouring a bit more aggressively or adding a gentle shake or swirl after your pour. A light swirl after the final pour can also help level the coffee bed and move any grounds off the filter walls.

That said, agitation is not always beneficial. Too much can lead to over-extraction, depending on the coffee and other variables. Since agitation increases energy and extraction, beans that already extract easily don’t need the extra help. Excessive agitation can also disturb fines, causing them to migrate into the filter and slow or even stall your brew, which increases the risk of over-extraction and bitterness. This risk is higher with coffees that naturally produce more fines, such as those from certain processing methods, specific origins, or when using grinders that generate more fines.

It’s also challenging to remain consistent from brew to brew if you’re not intentional with your agitation method.

If you choose to agitate, stick with one technique—whether stirring, shaking, or swirling. You may also consider using a drip assist tool like the Melodrip if you need help managing agitation or if you don’t have a gooseneck kettle. Agitation isn’t inherently bad—it can be incredibly useful when applied correctly. However, when used improperly, it can create more problems than benefits. Use it intentionally, and you’ll have a powerful tool for dialing in your perfect cup.

Water

Usually, temperature is the main focus when considering the water variable in brewing. But there’s more to it than simply hitting the right number. You can also use temperature profiling to target specific compounds you want to extract while avoiding those you don’t. Just as important is the mineral makeup of your water—or at least its hardness—since this can either elevate or ruin even the best coffee beans.

There will always be debate around the ideal brewing temperature because so many factors come into play. The reality is, you’ll never find a perfect, one-size-fits-all temperature for every brew. Instead, you should use general guidelines and adjust based on the coffee you’re using, other variables in play, and—most importantly—taste.

As a general rule, I start at 92°C and adjust from there. For darker roasts, I’ll drop the temperature, while for lighter roasts, I’ll raise it (but never above 95°C). For decaf, I typically lower it by a couple of degrees. Origin and processing method also influence my starting point. For example, with a dark-roasted, washed Ethiopian, I might start around 90°C: lowered slightly for the dark roast, but nudged back up because it’s a dense, washed bean that can handle more heat. After tasting, I’ll decide whether to adjust the temperature further or tweak another variable.

Here are some general guidelines that can help you get closer to your target on the first try:

• Start with 92°C as a baseline.

• For decaf, drop 3–5°C (decaf extracts more easily).

• For washed coffees, raise 2–3°C (they can handle more heat and agitation).

• For natural processed, drop 2–3°C (they can over-extract and turn “funky”).

• For heavily processed (anaerobic, carbonic maceration, etc.), drop 2–4°C (to avoid excessive funkiness).

• For high-altitude, dense beans, raise 2–3°C (they’re harder to extract).

• For freshly roasted beans (within the last week), drop 3–6°C (to avoid bitterness caused by high CO₂ levels).

  
  

These are just starting points—you still need to account for dose, grind size, brewer, and other variables. Another important factor that some people forget about - altitude. Water boils at different levels depending on altitude, so you may need to adjust what others recommend for a coffee by as much as 5 degree depending on where you live.

You can also experiment with temperature profiling throughout the brew. A cooler bloom helps preserve volatile aromatic compounds, improving both aroma and flavor. Raising the temperature for subsequent pours boosts extraction, which is helpful for denser beans. Lowering the temperature for the final pour—or during an immersion phase in a hybrid brew—can help avoid pulling out harsher compounds at the end. I recommend starting with a cool bloom, then increasing the temperature for the main pours. If experimenting with hybrid methods, consider lowering the temperature during immersion to keep flavors balanced.

Once you’ve addressed temperature, the next crucial element is water quality. Coffee is 98–99% water, so the water you use can make or break your brew. Good drinking water doesn’t necessarily equal good brewing water. The key factors are hardness and alkalinity. If your water is too hard, acidity disappears, and your coffee tastes flat, like old diner coffee. Too much alkalinity, on the other hand, can make it overly sharp or sour. The goal is the right balance: enough bicarbonate to tame acidity without destroying it, and the right mineral content to let flavors shine without dullness or harshness.

The simplest approach is to use a concentrate like Third Wave Water, Lotus Drops, or Apax Labs added to distilled water, which gives you a neutral starting point. Alternatively, you can use a $5 TDS meter: mix tap water with distilled until you reach around 75–90 ppm. While this isn’t as precise, it’s far better than using straight tap water.

In short, you want water that enhances your coffee rather than killing it, and you want to use temperature intentionally to bring out the flavors you want while avoiding those you don’t.

Conclusion

So now you know all the variables you can manipulate and how to do so, so you can try to dial in your favorite cup of coffee. In the next post we will look at some common issues you may run into when brewing and discuss how you can address them using the variables we just discussed.