General Hydroponics CaliMagic, 6-Gallon
✅ PROS
- 2-1-0 NPK with 2% calcium and 1% magnesium — prevents blossom end rot and tip burn in one additive
- 6-gallon size delivers roughly 1,536 teaspoons of concentrate, enough for 768 gallons of nutrient solution at 2 tsp/gal
- Works in both hydro and soil/coco when using RO water or low-EC tap water
❌ CONS
- No nitrogen-free version — growers running high-N regimes need to adjust base nutrients downward
- The 6-gallon jug is heavy (about 50 lbs) and has no handle — budget for a pump or extra hands
- Not a fix for existing deficiencies; it's preventative, so late-stage corrections will need a stronger product
The Verdict
The 6-Gallon Commitment: Is CaliMagic Worth the Space?
If you’re growing with reverse osmosis water or growing in coco coir, you already know the pain: calcium and magnesium deficiencies that show up as brown spots, curled leaves, and rotten fruit bottoms. General Hydroponics CaliMagic is the standard fix, and the 6-gallon size is the bulk option for serious growers. Here’s what you actually get.
What’s in the jug: 6 gallons of concentrated liquid nutrient with an NPK of 2-1-0, plus 2% chelated calcium and 1% magnesium. It’s a dark brown liquid that smells mildly earthy. The label calls for 2 teaspoons per gallon for general feeding, 1 teaspoon per gallon for light feeding. That works out to roughly 768 gallons of mixed nutrient solution per jug — enough to carry a 4-plant tent through several full cycles.
Build quality and handling: The HDPE jug is thick and durable. The cap seals well, and the label includes a full dosage chart that’s actually readable (rare for this category). But at 50 pounds, this isn’t a pour-and-go product. There’s no handle molded into the 6-gallon jug — a significant oversight. You’ll want a transfer pump or a friend. One Amazon reviewer noted: “Great product, but I nearly threw my back out on the first pour. Get a pump.” That’s fair warning.
Performance in real grows: CaliMagic does exactly what it claims. If you’re using RO water, it replaces the minerals that RO strips out. In coco, it prevents the classic “coco calmag deficiency” that shows up around week 3 of flower. Users consistently report it clears up interveinal chlorosis (yellowing between leaf veins) and prevents blossom end rot in tomatoes and peppers. One reviewer put it plainly: “My tap water is garbage, so I’ve used this for three years. No deficiencies, no problems. It’s boring and reliable.”
Where it falls short: First, it’s a preventative, not a cure. If you already have severe deficiency symptoms, you’ll need a faster-acting product. Second, the 2-1-0 NPK means you’re adding a small amount of nitrogen every time you dose. In late flower, when you’re cutting N, that can throw off your ratios if you don’t adjust your base nutrients. Third, the lack of a handle on a 50-pound jug is a genuine design flaw. And for small growers with 1-2 plants, the 6-gallon size is overkill — the 1-gallon or quart sizes make more sense unless you’re running multiple cycles.
Who should buy this:
- Coco and hydro growers using RO water — this is non-negotiable, you need calmag
- Tomato and pepper gardeners dealing with blossom end rot in containers
- Multi-plant indoor growers running 4+ plants who’ll use it within 12 months
- Skip it if you’re on good tap water (100+ ppm) growing in soil — you may not need it, and you’ll be storing 50 pounds of liquid
Frequently asked questions:
Q: Can I use CaliMagic with tap water? A: Yes, but check your water report first. If your tap water is above 150 ppm, you may already have enough calcium and magnesium. CaliMagic is designed for low-EC water sources like RO, distilled, or very soft tap.
Q: How often should I add it? A: Every feeding at 2 tsp/gal for most plants, every other feeding at 1 tsp/gal for light feeders. Mix it into your water before adding base nutrients to prevent precipitation.
Q: Does it work for soil grows? A: Yes, especially for container soil with peat or coco bases. For in-ground garden soil, test first — most native soils already have adequate calcium.
The Verdict:
Buy it if: You’re growing in coco or hydro with RO water, or you’re fighting blossom end rot and want a reliable preventative. At 768 gallons per jug, the cost per gallon of mixed solution is trivial.
Skip it if: You’re a small-scale grower with one or two plants (buy the quart), you’re on hard tap water, or you need a fast-acting fix for an existing deficiency.
Rating: 4.6/5 — Half a star off for the missing handle and the nitrogen content in late flower. Otherwise, it’s the standard for a reason.