How to Top Off Your Tank with Water and Plant Food

Tank Top-offs maintain nutrient stability between Tank Refreshes.

After a Tank Refresh sets a clean nutrient baseline, your plants continuously absorb water and nutrients every day. As water levels drops, the nutrient concentration in your tank can shift. Topping off with the correct amount of water + plant food per gallon keeps that ratio stable and support consistent growth.

Your first regular Tank Top-off will likely happen after you transition to Standard Dose (a full-tank dosing step). From that point forward, Tank top-offs shift to maintenance dosing where plant food is measured per gallon added, not the full tank.

Early in the grow cycle, plants drink less. As they mature, water uptake increases and top-offs become more frequent.

Simple framework:

• Tank Refresh= Reset

• Tank Top-off = Maintain

Top-offs don’t replace Tank Refreshes, they preserve the nutrient stability until your next reset. For best results, keep your tank at least half full and always dose plant food based on your plants’ current growth stage.

• What: Add water and the correct plant food dose per gallon to keep nutrients stable gallon by gallon.

• When:

  • Devices with active membership will receive a Kelby Tank Top-off Task in the app

  • Devices without an active membership should strive to top-off at least 1x per week

• In-app help: Tap Help (at the bottom of the Home screen) → Get guided help → Plants, Pests & Growing Environment → Topping off your tank

• Why it matters: Consistent top-offs help prevent nutrient swings that can stress plants.

• Be sure to topoff to Full:

  • Tank size: Gardyn Home = 5 gallons| Gardyn Studio = 4 gallons

• Target: Keep your tank above 1/2 full or more for optimal growth

• This guide is for regular top-offs, (not first time plant food, or the transition to standard dose).

• If you are adding plant food for the first time after starting new plants, use the When and How to Add Plant Food for the First Time (Sprout Dose) guide.

• If you are Transitioning to Standard Dose, use the Transitioning to Standard Guide.

Dose based on your current growth stage:

• True leaves/Early Growth: 1/2 tsp per gallon

• Mature/Blooming/Fruiting: 1 tsp per gallon

If your Gardyn contains mixed plant stages, use the growth stage that represents the majority of your plants.

• Fill a clean 1-gallon container with warm tap water

• Add the correct plant food dose for 1 gallon (see section above)

• Shake or stir well until fully dissolved

  • If needed, mix inh 1/2 tsp increments for better dissolution.

Why dissolve first? Ensures even nutrient distribution and prevents concentration spikes.

Tip: Upcycle a clean 1-gallon jug (water jug, milk jug, etc.) Rinse well prior to first use.

• Remove the small wooden cap on the lid.

• Pour in the dissolved mixture into the tank.

• Add 1 gallon at a time (mix, pour, repeat) until you reach the tank capacity.

  • Active membership ensures you’ll always know exactly how many gallons to add.

  Full tank reference:

  • Home tank full = 5 gallons

  • Studio tank full = 4 gallons

HydroBoost supports system cleanliness and root health.

Dose varies by:

• Gardyn model (Home vs Studio)

• Water type

Follow the label or in-app instructions.

Keep your tank at least half full. Allowing water to drop too low increases the risk of nutrient imbalance. Consistent top-offs protect root health, growth rate and harvest quality.

Plant food won’t dissolve

Use warmer water, shake longer, and add plant food in smaller increments (½ tsp at a time).

Topped off with plain water

No stress. At your next top-off, mix plant food using the normal per-gallon dose for your growth stage. Avoid “catch-up” dosing.

Tank level drops quickly

Water use increases as plants mature. If the drop seems unusual, check for visible leaks and confirm the lid is fully seated.

Questions? Reach us at support@mygardyn.com, or chat with us. We're here to help!