Botanicare Clearex is the best flushing agent for cannabis nutrient burn. It is an isotonic salt solution, so it leaches built-up fertilizer salts from the medium while keeping osmotic pressure at the root surface stable, and it works in soil, coco, and hydro. Plain pH-adjusted water is the cheapest option and the correct first move when the burn is mild.
How do the top flushing options compare?
- Botanicare Clearex: best overall, gentle on roots, works in every medium.
- Advanced Nutrients Flawless Finish: best for the final flush before harvest.
- Fox Farm Sledgehammer: best for salt-heavy coco and rockwool runs.
- General Hydroponics FloraKleen: best budget concentrate for large reservoirs.
- pH-adjusted water: best free option for early or mild tip burn.
Why does Clearex take the top spot?
Nutrient burn is a salt accumulation problem, not a nutrient shortage. A flush works by dissolving those salts and carrying them out of the pot in the runoff. An isotonic product does that without pulling water out of the root cells, which is why plants usually look less droopy 24 hours after a Clearex flush than after a hard water-only drench.
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It also stays useful across the whole cycle. The same bottle handles a mid-vegetative burn correction and a pre-harvest flush, so you are not buying two products for one job.
Best flushing products for cannabis nutrient burn
Botanicare Clearex: best overall
A concentrated isotonic salt solution with a light, clean label rate. Mix it at the stated dose, water to runoff, and recheck runoff EC before you feed again. It is the safest pick for growers who have never flushed before.
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Advanced Nutrients Flawless Finish: best pre-harvest
Designed for the last week before chop rather than for correcting an active burn. If your tips are scorched in late flower and you are close to harvest, this is a reasonable substitute for a mid-cycle flush.
Fox Farm Sledgehammer: best for coco and rockwool
A yucca-based surfactant that helps water spread through dense coco coir and break up salt crust. Use it when runoff EC stays high after two plain-water passes.
General Hydroponics FloraKleen: best budget concentrate
Cheap per gallon and easy to dose in a reservoir. It is a solid choice for recirculating systems where you want to strip salts without draining and remixing the whole tank.
pH-adjusted water: best free option
For mild tip burn, plain water at the correct pH is enough. Skip the bottle, run two to three times the pot volume through the medium, and resume feeding at a lower strength.
Should you flush, or just feed lighter?
Flush first if runoff EC is far above your input EC, or if leaf tips are crisp and curling. If the burn is a few brown tips on older leaves and runoff reads close to input, drop your feed strength by 25 percent and keep going. Flushing a healthy plant costs you yield and days of growth.
How do you flush a cannabis plant with nutrient burn?
- Measure runoff pH and EC before you start so you have a baseline.
- Mix your flush agent at the label rate in pH-adjusted water.
- Pour through two to three times the pot volume, catching runoff.
- Recheck runoff EC and repeat until it sits near your target.
- Wait 24 to 48 hours, then resume feeding at 50 to 75 percent strength.
How much water does a flush take?
Plan on two to three times the volume of the container for a mild correction, and up to five times for a badly salted pot. A 5-gallon pot with heavy salt buildup can take 15 to 25 gallons of flush water. Catch and test the runoff rather than guessing.
Does flushing fix nutrient burn overnight?
No. Damaged leaf tips stay damaged, and they will not green back up. What improves is new growth, which usually shows a healthier color within a week to ten days.
Can you flush too much?
Yes. Repeated flushing strips micronutrients, stalls growth, and leaves the medium waterlogged, which invites root problems. Flush once, verify with runoff numbers, then return to a lighter feed schedule.
What should you buy?
Start with Clearex if you want one bottle that handles both burn correction and pre-harvest. Add Sledgehammer only if you grow in coco, and keep a pH pen handy because every flush on this list depends on accurate input pH.