Most hobbyists dose based on the "Gross Volume"—the size of the glass box. However, a 20-gallon tank rarely holds 20 gallons of water. Once you add substrate, rocks, and wood, the actual water volume can drop by 20% or more.

Common Displacement Factors:

• Substrate: 1 inch of sand in a 10g tank displaces ~0.7 gallons.
• Hardscape: Large rocks like Seiryu or Dragon Stone are dense and displace significant volume.
• Equipment: Internal filters, heaters, and large sponge filters all take up space.

Overdosing medications or fertilizers by 20% might not kill a hardy goldfish, but it can be fatal for sensitive species like Caridina shrimp or Discus.

💧 Dechlorinators (Water Conditioners)

The most frequent dose you'll give. If you use a hose to fill your tank, dose for the entire tank volume. If you use buckets, dose only for the volume of the bucket.

Tip: Seachem Prime can be dosed up to 5x the standard amount in emergencies to detoxify ammonia.

🌿 Plant Fertilizers

Plants need a balance of Macros (N, P, K) and Micros (Iron, Trace). Dosing too much leads to algae; dosing too little leads to stunted growth and melting leaves.

Tip: Consistency is more important than quantity. Daily micro-dosing is often better than one large weekly dose.

💊 Medications & Treatments

Medications are easily the most dangerous things we put in our tanks. If you're using copper-based treatments like Cupramine, you've got to use a test kit—the line between "curing" and "crashing" is incredibly thin.

⚠️ CRITICAL: Copper and many other medications are lethal to snails and shrimp. Don't dose them in a tank where you want your invertebrates to stay alive.

Tip: Always remove activated carbon from your filter before dosing medications, as it'll absorb the active ingredients before they can work.

I've learned that dosing is only half the battle. If you don't understand what's happening in your water, you're just guessing. Here's the breakdown of what we're actually looking for:

Dosing by "capfuls" is a recipe for disaster. I've found that being precise makes everything easier. Here's what we use:

• Oral Syringes (1ml, 5ml, 10ml): You can grab these at any pharmacy. They're perfect for getting those exact milliliter measurements.
• Plastic Pipettes: These are great for spot-dosing algae or target-feeding your corals.
• Graduated Cylinders: Use these for the big stuff, like measuring dechlorinator for a massive water change.
• Digital Scales: If you're like me and prefer mixing your own "dry salts," a scale is non-negotiable.

*Stability dose varies by day. Check guide for details.

Here's a typical weekly routine I use for a low-to-medium tech planted tank. It's not set in stone, but it's a solid starting point:

Before you add anything to your tank, run through this quick list. It's saved me more than once:

• ✅ Double-Check Your Math: I always calculate twice because it's way easier than fixing an overdose.
• ✅ Observe Your Livestock: I stick around for 20 minutes after dosing. If they're gasping at the surface, something's wrong—time for a water change.
• ✅ Check Expiry Dates: Old meds and bacteria can go bad or even become toxic.
• ✅ Store Safely: Keep all aquarium chemicals out of reach of children and pets.