Cyco Swell — Late-Stage Flowering Additive for Bigger, Better Blooms
Best for: Growers in weeks 5-7 of flowering who want to maximise flower size, density, and sweetness without overcomplicating their feed
Our thoughts
Cyco Swell is the kind of additive that actually delivers what it promises. Growers have been using this for years because it works consistently. If you're running hydro and want to squeeze the best out of the final flowering stage, this is a solid choice at a reasonable price point. Pharmaceutical-grade ingredients, proper dosing, minimal fuss.
Cyco Swell is a liquid phosphorus and potassium booster formulated specifically for the final three weeks of flowering. It's not a base nutrient—it's a targeted finishing additive designed to work alongside your existing feeding program. During weeks 5-7, when plants are pouring energy into flower development, Cyco Swell supplies the phosphorus and potassium they're craving, plus magnesium to activate the enzymes that drive growth. The result is bigger, denser blooms with improved sweetness and stalk strength. Made using pharmaceutical-grade ingredients, it's one we recommend a lot for growers running hydroponic systems who want measurable results without guessing.
How it compares
Cyco Swell sits in the balanced PK booster category—not an extreme hit like Mad Farmer M.O.A.B., but more refined than basic liquid KoolBloom.
- 1-5-3 NPK formulation: modest nitrogen, solid phosphorus spike, good potassium hit
- Includes magnesium—most competitors don't, but it matters for enzyme activation
- Pharmaceutical-grade filtration ensures consistency batch to batch
- Sits mid-to-premium on price, but growers using it for years suggest reliability over flashy marketing
In plain terms: not the most aggressive bloom booster on the market, but the one that works cleanly with established nutrient lines and doesn't cause issues.
Usage guidance
When to apply
Weeks 5-7 of flowering, typically the second half of your bloom cycle. This is when phosphorus and potassium demand peaks and flower size is determined.
How to use
Add 2.5ml per litre of water to your nutrient reservoir. This will increase solution PPM by roughly 200. Use alongside your regular base nutrient—don't replace it. Cyco Swell is an additive, not a complete feed.
Compatibility
Works with any balanced hydroponic base nutrient. Don't mix with Cyco Potash Plus, as you'd be doubling up on potassium unnecessarily.
System type
Equally suited to hand feeding, drip irrigation, or flood-and-drain hydro. The liquid format dissolves cleanly and won't clog lines.
Technical specifications
- NPK Analysis: 1-5-3
- Water-soluble magnesium: 1%
- Dosage: 2.5ml per litre
- PPM increase per dose: Approximately 200
- Application timing: Weeks 5-7 of flowering (final 3 weeks before harvest)
- Available sizes: 1L, 5L, 20L
- Formulation grade: Pharmaceutical-grade ingredients with 1-micron filtration
Who this is for
- Hydroponic growers in their final flowering stage wanting proven, reliable results
- Anyone running established nutrient lines who wants a compatible finishing booster
- Growers prioritising flower density and sweetness over extreme size
- First-time additive users who want something that works without requiring constant tweaking
Particularly well suited to structured growing setups where consistency and compatibility with existing systems matter more than marketing hype.
Our take
Cyco Swell does exactly what it should in the final weeks of flowering: supplies the nutrients plants actually need at that stage, activates the enzymes that matter, and doesn't cause compatibility headaches with your main feed.
If you're running hydro and want to finish strong without overcomplicating things, worth picking up while stock lasts. Growers have been using this for years for good reason.
