Nutrient and Supplement Feeding Schedule

I’ve created a nutrient and supplement feeding schedule for RDWC cannabis cultivation that you can download and customize for your needs. There are two versions—one for systems using CO₂ and another for systems without CO₂—so make sure you choose the right one. Although these nutrients and supplements can work in other hydroponic setups, the dosages are specifically tailored for RDWC, which typically features higher oxygen levels. You can multiply the number of gallons in your system by the mL to add per gallon and replace the amount to add per gallon with the total amount of nutrient or supplement to be added for the week. The schedules also include a row to plan the weeks that you will be doing a complete flush of your system which can help reduce nutrient and supplement costs for each growth cycle. a row to plan CO₂ target levels each week to bring down the CO₂ costs, and another row for tracking a safe light intensity range to use for each week.

To use the schedule, multiply the number of gallons in your system by the mL-per-gallon dose, then replace the per-gallon amount with the total weekly amount. Each schedule is available in Microsoft Excel (.xlsx) or Adobe PDF (.pdf) format and covers a 6-week veg phase with 8-week flowering phase with an additional week for flushing your system.

Weekly TDS Ranges, Light Intensity Ranges, CO₂ Levels and Complete System Flushes

There is Feeding Schedule for both, CO₂ and non-CO₂ systems, that includes a recommended TDS range, light intensity range, CO₂ level, and another row where you can track when to flush your system saving money on nutrient and supplement costs over each growth cycle and reducing water costs.

Customizing the Schedule

You can adjust weekly dates and nutrient amounts in the spreadsheet to fit your specific system. Just replace my values that show the mL of each nutrient to add for each gallon of water with your own total mL for each supplement or nutrient. This makes it easy to plan your weekly feedings.

I’ve also included rows I use for tracking CO₂ levels, light intensity ranges and when to do a complete system flush. Feel free to use or adapt them if you’re interested in lowering your own expenses.

Flushing and Nutrient Changes

“Water Flushing” weeks are marked in the schedule to show when I fully drain and refill my system before adding new nutrients. Flushing is important whenever the nutrients or their amounts change significantly from one week to the next. If there’s no major change, you can skip a weekly flush to save on nutrient costs. Just calculate how many percent of nutrients you want to add and use than multiple by each nutrient amount you would add if you flushed to get the amount of each nutrient you should top off.

Determining Your Water Volume in RDWC

Accurate mL‐per‐gallon dosing requires knowing how many actual gallons your system holds. A “13‐gallon” bucket will hold less than 13 gallons of water, and you need to look at the size of the net pot that came with your system before you can be sure what it actually holds.

8 Gallon Buckets

1. 5″ Net Pot: Typically holds ~6 to 6.5 gallons in an 8‐gallon RDWC bucket (water line ~1–2″ below net pot).
2. 8″ Net Pot: Usually holds ~5 to 5.5 gallons per bucket due to deeper pot displacement and a slightly lower fill line.

13 Gallon Buckets

1. 5″ Net Pot: Typically holds ~11 gallons in a 13‐gallon RDWC bucket (water line ~1–2″ below net pot).
2. 8″ Net Pot: Usually holds ~9 gallons per bucket due to deeper pot displacement and a slightly lower fill line.

Example: If you have a 13-gallon system with 4 plant sites + 1 reservoir = 5 total buckets, each with an 8″ net pot, then 5 × 9 = 45 gallons.

Using the Nutrient & Supplement Schedules

1. Multiply the per‐gallon dose (mL/gal) by your total gallons to get each product’s weekly total.
2. Mix nutrients separately: Never pour A and B together undiluted. Let each circulate ~15 minutes before adding the next.
3. pH Control: After adding A and B, adjust pH to ~5.8 in RDWC, then proceed with other supplements.
4. Wait ~15 minutes for each item to circulate before adding another.

Feeding Schedule (6 Week Veg / 8 Week Flower for RDWC Hydroponic Systems)

• Aggressive Feeding Schedule for systems without CO₂ enhancement available in Microsoft Excel (.xlsx) or Adobe PDF (.pdf) format.
• Normal Feeding Schedule for systems with CO₂ enhancement available in Microsoft Excel (.xlsx) or Adobe PDF (.pdf) format.

Most of the nutrients and supplements shown on the Nutrient Feeding Schedule are from House & Garden, with a few that are from other manufacturers. A detailed description for the purpose of all the products shown on this schedule on Grow Tent Planning Guide – Phase 1.

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