FoxFarm Big Bloom Review: pH & EC Test Results

Last updated: August 2026

Quick answer: HWGrow mixed 1 mL of FoxFarm Big Bloom 0-0.5-0.7 into 500 mL of reverse-osmosis water. That is 2 mL/L, or about 7.6 mL per U.S. gallon. The two pH meters moved from 6.14 and 6.31 to 6.75 and 6.95, while the video reported an increase of roughly 100 conductivity-based PPM. Useful result? Yes. Proof that Big Bloom always raises pH, balances Grow Big, improves terpenes or should never be used above 10 mL per gallon? No.

Video chapters: Big Bloom pH and PPM test

1. 0:00 — The “soil juice” explanation
2. 0:13 — Why “Bloom” in the name can be confusing
3. 0:35 — Starting pH readings
4. 0:44 — Final pH readings
5. 1:01 — Ten-minute pH drift
6. 1:08 — Solubility and hydro claim; corrected below
7. 1:16 — OMRI Listed label
8. 1:20 — Conductivity-based PPM change
9. 1:37 — Label-dose extrapolation; limits explained below
10. 1:58 — Historical personal dose; not a universal schedule

Selecting a timestamp opens the video at that moment without moving you away from this section.

What is FoxFarm Big Bloom?

“Soil juice” is honestly a useful beginner shorthand. Big Bloom is a low-analysis liquid made with bat guano and earthworm castings. Its current guaranteed analysis is 0-0.5-0.7, and FoxFarm says it can be used during every stage of plant growth—not only flowering. It is also currently OMRI Listed and registered as a California organic input material.

That does not make it mystery magic. The label tells us what is guaranteed; it does not justify saying the bottle contains every trace element, and this screen did not test terpene production, yield or finished-flower quality. Read FoxFarm’s current Big Bloom analysis and directions.

HWGrow Big Bloom test results

The test rate matters: this was not 1 mL per gallon. It was 1 mL in half a liter, roughly one-eighth of FoxFarm’s current 60 mL-per-gallon general-feeding direction. The separate HWGrow nutrient-test protocol explains why the same ratio, temperature, water and meter scale must be recorded before comparing products.

What the results really tell you

Big Bloom raised pH in this low-buffer RO sample

Both pH meters moved by a similar amount, so the direction of the change is worth recording. But RO water has little buffering capacity. The same bottle can behave differently in tap water or a complete nutrient mix. Big Bloom and Grow Big also should not be treated as automatic pH-up and pH-down partners; measure the finished recipe, let it settle, and adjust only if needed.

The ten-minute drift did not prove “low solubility”

A reading can drift because the suspension is still mixing, the sensor is stabilizing, temperature is changing or the sample is releasing gas. This video did not isolate the cause. FoxFarm’s current directions say Big Bloom can be applied through drip irrigation and a no-clog hose-end sprayer. That does not guarantee compatibility with every recirculating system, pump or emitter, so shake the bottle, keep organic suspensions mixed, inspect lines and follow the equipment and fertilizer directions for your exact system.

The PPM number is a conductivity conversion

The meters did not count fertilizer particles or identify individual nutrients. They measured electrical conductivity and converted it to a PPM-style display. Because the video did not name the 500, 640 or 700 conversion scale, the approximate +100 PPM observation is useful only as a historical within-test comparison. A straight-line estimate to 60 mL per gallon is not a separately mixed measurement or a plant trial.

OMRI Listed is useful—but specific

OMRI listing means the input has been reviewed for use under organic standards. It does not prove that every crop grown with it is certified organic, that the product improves flavor, or that it is the right dose for every medium. Those are separate questions.

Why the old dose and terpene conclusions were too strong

The original page called FoxFarm’s 60 mL-per-gallon direction absurd and recommended no more than 0–10 mL per gallon. It also suggested unlisted trace ingredients could improve terpene production. The pH/PPM screen did not measure plant response, tissue nutrients, terpenes, yield or flower quality, so it cannot prove those claims.

• FoxFarm’s current general direction remains 60 mL per gallon every other watering, with different rates for heavy feeding, seedlings/transplants and foliar use.
• The video used one-eighth of that general rate and extrapolated from one measured preparation.
• Big Bloom may be used alongside other fertilizers, so the complete recipe—not one bottle in isolation—sets final pH and conductivity.
• Medium charge, irrigation frequency, source-water alkalinity, plant stage and response all matter.

The practical rule is simple: start from the current label and your established program, measure the full mix, and adjust from repeatable plant and root-zone data. Do not use either the bottle maximum or HWGrow’s old personal dose as a universal cannabis schedule.

How to use Big Bloom without guessing

1. Shake it thoroughly. Big Bloom contains suspended organic ingredients, so remix the bottle before measuring.
2. Confirm the current label. Rates can differ by application and product revision.
3. Measure your source water. Record pH and EC. Search your ZIP code plus “water report” for local alkalinity and mineral information when available.
4. Dilute concentrates one at a time. Add Big Bloom to water, stir well, then add the next product. Never combine concentrates before dilution.
5. Measure the complete feed. Record final pH and EC, or name the PPM conversion scale if that is the display you use.
6. Let the mix stabilize. If values are moving, keep mixing and wait for a steady reading instead of choosing the first number.
7. Watch the delivery system. Inspect emitters, tubing and reservoirs when running organic suspensions.
8. Judge trends, not one runoff sample. Pair the measurements with plant stage, medium, irrigation history and visible response.

Use the nutrient mixing-order guide for safe dilution, the runoff testing guide for trend interpretation, and the fabric-pot feeding guide for a repeatable irrigation workflow.

Big Bloom test limitations

Recommended Big Bloom and testing supplies

FoxFarm Big Bloom 0-0.5-0.7The low-analysis earthworm-casting and bat-guano liquid tested here. Verify the current bottle and application rate.
Buy It Now



FoxFarm Soil Liquid TrioBig Bloom is commonly used as one part of this three-bottle soil program. Dilute each concentrate separately and test the complete mix.
Buy It Now



pH and EC meter kitMeasure source water, the complete feed and runoff. Calibrate the probes and record EC or the named PPM scale.
Buy It Now

Affiliate disclosure: HWGrow may earn a commission from qualifying purchases at no additional cost to you. Product destinations may be replaced with equivalent items; always verify the exact formula, label and system compatibility before use.

Want the full feeding workflow?

This page explains one controlled product screen. The Grow With Me Masterclass connects mixing, watering, runoff and plant response inside a complete guided workflow without reproducing protected lesson content here. If your numbers disagree, ask HWGrow a question and include the exact bottle, lot, dose, water source, full recipe, temperature, pH, EC/PPM scale, medium and plant stage.

FoxFarm Big Bloom FAQ

Is Big Bloom only for flowering?

No. Despite the name, FoxFarm currently says Big Bloom can be used throughout all stages of plant growth. Use the rate for the intended application.

Did HWGrow test the 60 mL-per-gallon label dose?

No. The test used 1 mL in 500 mL, equivalent to about 7.6 mL per gallon. The higher-dose PPM number in the video was a mathematical extrapolation, not a separately mixed sample.

Does Big Bloom always raise pH?

No. It raised pH by about 0.6 unit in this low-buffer RO sample. Source-water alkalinity, temperature and the rest of the recipe can change the result.

Does Big Bloom improve cannabis terpenes?

This test did not measure terpenes or compare treated and untreated plants, so it cannot answer that question.

Can Big Bloom be used in hydro or drip irrigation?

FoxFarm’s current directions allow drip irrigation and a no-clog hose-end sprayer, but that does not guarantee compatibility with every recirculating system or emitter. Follow the current label and equipment guidance, maintain agitation where appropriate and inspect the system.