Most dosing mistakes aren't chemistry problems. They're spoon problems. One letter separates a tablespoon from a teaspoon, and that letter is a factor of three. This is the plain version: what the units mean, how many feedings a container makes, and how to work out what one feeding costs.
The Short Version
- 1 tablespoon (tbsp) = 3 teaspoons (tsp). So 1/4 tbsp is 3/4 tsp, which is three times a 1/4 tsp dose, not four times.
- One feeding is one US gallon of water mixed at a stated dose: the base dose on the feeding chart for powders, the dose printed on the label for liquids.
- At the base dose, a 1 lb bag of Incredible Bulk makes 128 feedings and a 1 lb bag of Kelp It Real makes 400.
- The label says a 16 fl oz bottle of Microbes treats 157 gallons at 3 ml per gallon, and a 16 fl oz bottle of Phishy or Vitamin Sea treats 94 gallons at 5 ml per gallon.
- Always count from the size printed in the product name (1 lb, 8 oz, 16 fl oz), never from shipping weight.
Unit Conversions
Powders are measured with spoons. Liquids are measured in milliliters or spoons. These are standard kitchen conversions, and they are close enough for feeding plants.
- 1 tbsp = 3 tsp, about 15 ml
- 1 tsp = about 5 ml
- 1/4 tbsp = 3/4 tsp, about 3.7 ml
- 1/4 tsp = about 1.2 ml
- 1 US gallon = 128 fl oz
- 1 fl oz = about 30 ml
For liquids, 16 fl oz is 473 ml and 32 fl oz is 946 ml. We always write 32 fl oz.
Tbsp versus tsp
The abbreviations differ by one letter and the volumes differ by a factor of three. Read the letter. The base dose of Incredible Bulk on the feeding chart is 1/4 tbsp per gallon. Kelp It Real is 1/4 tsp per gallon. They are not interchangeable.
Ounces of weight versus fluid ounces
On a powder, "8 oz" or "1 lb" is weight. On a liquid, "16 fl oz" is volume. A dry ounce and a fluid ounce are different measures, so don't use one to estimate the other. A tablespoon is a volume, so a level tablespoon of a powder weighs whatever that powder weighs.
How Many Feedings Does a Container Make?
Growganica stores a feedings-per-ounce figure for each powder. For Incredible Bulk and Kelp It Real, it rests on the base dose on the feeding chart. Multiply by the net quantity in the size name, never the shipping weight, which includes packaging.
Powders
- Incredible Bulk: base dose 1/4 tbsp per gallon, 8 feedings per oz, 128 feedings in a 1 lb bag.
- Kelp It Real: base dose 1/4 tsp per gallon, 25 feedings per oz, 400 feedings in a 1 lb bag.
The same arithmetic works for other sizes. Incredible Bulk 3 lb is 3 x 128 = 384 feedings. Kelp It Real 8 oz is 8 x 25 = 200 feedings.
Liquids (label figures)
Liquid labels print gallons per bottle at one stated dose. For Microbes and Phishy, that dose is the top of the feeding chart range, not the base. The base for both is 1 ml per gallon. Vitamin Sea has a single chart dose.
- Microbes: label dose 3 ml per gallon (chart range 1 to 3 ml). A 16 fl oz bottle treats 157 gallons, a 32 fl oz bottle treats 315 gallons.
- Phishy: label dose 5 ml per gallon (chart range 1 to 5 ml). A 16 fl oz bottle treats 94 gallons, a 32 fl oz bottle treats 189 gallons.
- Vitamin Sea: 5 ml per gallon, a single chart dose. A 16 fl oz bottle treats 94 gallons, a 32 fl oz bottle treats 189 gallons.
A lower dose treats more gallons from the same bottle, and a higher dose treats fewer. We don't publish a feedings figure for the 1 ml base of Microbes and Phishy, so plan around the label gallons above. Phishy was sold as SeaPhood, so older pages may use that name.
Veg, Bloom and King Krustacean
We don't publish a feedings-per-bag figure for these three right now. The feedings number we have stored for them doesn't match the dose on the feeding chart, and the chart is the source of truth for dose. The number is being reconciled. Until it is, use the dose on the feeding chart and don't divide a bag by a figure you saw elsewhere.
Worked Cost Per Feeding
Take a 1 lb bag of Incredible Bulk.
- Feedings: 1 lb x 128 feedings per lb = 128 feedings.
- Price: $28.99 for 1 lb, the registry price as of 2026-09-11.
- Cost: $28.99 / 128 = $0.2265, about $0.23 per feeding.
That is the cost of one gallon of feed at the base dose. Prices change, so check the product page for today's price before you rely on this number. The method stays the same: price divided by feedings. If you dose at twice the base amount, you use twice as much per gallon and the cost per feeding doubles. A bag only lasts as long as the dose you actually mix.
What to Do: Scoop Level, Every Time
The feedings per bag above come from the feeding chart, not from the weight of a scoop. Dose by volume, using the spoon size on the chart. What you control is keeping every scoop the same size: powders pack differently depending on how you scoop, and a heaped or pressed scoop is a bigger dose than a level one.
- Use the spoon the chart names: a tablespoon for tbsp doses, a teaspoon for tsp doses.
- Fill the spoon, then scrape the top flat with a knife.
- Don't tamp or press the powder down.
- Note the dose and the spoon you used for each batch, so the next batch matches.
For liquids, a measuring syringe or small graduated cup marked in ml beats a kitchen spoon. Measure the ml, then add water.
Optional check
To test how steady your scooping is, zero a small cup on a kitchen scale, add ten level scoops and divide the total grams by ten. Repeat on another day. Similar numbers mean steady technique. This is a rough sanity check, not a way to count feedings: the feedings per bag come from the feeding chart. If level, untamped scoops use up a bag far faster than the feedings above suggest, contact support with the product, the size and the dose you mixed.
Where Growganica Fits
Every Growganica product has a dose per gallon on the feeding chart, and the container size tells you how far it goes. Incredible Bulk and Kelp It Real are the clearest examples above because their feedings per bag are set at the base dose. Microbes, Phishy and Vitamin Sea are covered by the label gallons per bottle, at the label dose in the list above.
Veg and Bloom need Microbes to work as designed, so count a Microbes bottle into your plan if you feed either. For the schedule by plant, use the feeding chart.
Frequently Asked Questions
How many feedings are in a 1 lb bag?
At the base dose on the feeding chart, a 1 lb bag of Incredible Bulk makes 128 feedings and a 1 lb bag of Kelp It Real makes 400. One feeding is one US gallon of water mixed at that dose. For Veg, Bloom and King Krustacean we don't publish a feedings-per-bag figure right now, so use the dose on the feeding chart.
Is the dose 1/4 tsp or 1/4 tbsp?
It depends on the product, and the two are not interchangeable. The base dose of Incredible Bulk on the feeding chart is 1/4 tbsp per gallon. Kelp It Real is 1/4 tsp per gallon. Since 1 tbsp is 3 tsp, 1/4 tbsp is 3/4 tsp, which is three times a 1/4 tsp dose.
How many gallons does a 16 oz bottle treat?
The label says a 16 fl oz bottle of Microbes treats 157 gallons at 3 ml per gallon, and a 16 fl oz bottle of Phishy or Vitamin Sea treats 94 gallons at 5 ml per gallon. For Microbes and Phishy those label doses are the top of the feeding chart range, so a lower dose treats more gallons.