Two secondary nutrients, two jobs
Magnesium forms the centre of chlorophyll. Calcium supports cell wall strength. Monkey Mag Cal supplies both secondary nutrients with trace elements. The product is particularly relevant to soft water, reverse-osmosis water and coco growing. Those use cases explain why the bottle exists; they do not establish a diagnosis from a photograph. If a plant looks unhealthy, record the medium, water source, current programme and recent changes before assuming a single nutrient is missing. Several variables can look similar when all you see is a damaged leaf.
Why coco changes the conversation
Coco has high cation exchange capacity and can bind calcium and magnesium. That is why the Monkey feeding chart specifically says to use Mag Cal for coco. A grower moving from soil to coco should not simply copy every previous decision without considering the new medium. Equally, a grower using RO water should make that fact clear when speaking to a stockist. A useful question is not just whether to buy cal mag, but how it fits with the complete base nutrient system, medium and water source already in use.
The Mag Cal dose
Mag Cal: 1–2 ml per litre. Do not add it in the flush week. Feeding is the same in DWC and hydro.
Analysis
| Nutrient / constituent | Content |
|---|---|
| Nitrogen (N) | 2.9% |
| Calcium oxide (CaO) | 5.0% |
| Magnesium oxide (MgO) | 2.5% |
| Iron (Fe) | 0.04% |
| Manganese (Mn) | 0.01% |
| Zinc (Zn) | 0.006% |
From the label
- Compound fluid fertilizer with trace elements
- Mag Cal: 1–2 ml per litre. Do not add it in the flush week. Feeding is the same in DWC and hydro.
- Suitable for all growing media and all stages of the plant’s life cycle
- Shake well before use
- Store in a cool, dark place
- Made in the UK
- Manufacturer (printed on the label): JS GARDEN RECLAIM LIMITED, Global House, 1 Ashley Avenue, Epsom KT18 5FL, United Kingdom; info@monkeynutrients.co.uk.
Read the chart as a complete programme
The Monkey feeding chart is written as a ratio per 10 litres of water. Its headings distinguish vegetative growth, bloom and flush, and the programme toggle selects PK or Resin. Before measuring anything, check that the week on the screen is the week you intended. A veg week and a bloom week can share a number but involve different base feeds. The chart’s ranges should remain ranges in your notes. A displayed interval does not mean that the website has secretly chosen one precise value for your crop. Read the full row and the surrounding programme rather than lifting a number out of context. The calculator is a convenient way to change reservoir volume without changing the underlying chart. Enter litres, choose the week and programme, and read the millilitres for each included product. If you double the water volume, the confirmed amounts double; if you halve it, they halve. A product without a confirmed dose is not automatically assigned one. This simple boundary is important: arithmetic can scale an instruction, but it cannot supply missing product guidance.
Keep water, medium and environment in the picture
Monkey nutrients are intended for UK hard and soft water and for coco, soil and hydro. That gives a common framework, but it is still worth describing the grow accurately. Write down your medium, water source and programme so that a conversation with a stockist begins with useful information. For coco, the chart explicitly calls for Monkey Mag Cal. Its dose is 1–2 ml per litre. More information is not the same thing as more bottles. Clear inputs and a readable schedule are often the best starting point for a productive question. The chart also carries environmental reference information. It lists pH 5.5–6.5, temperature 20–27°C, and week-specific EC and humidity values. Normal and closed-room EC are separate rows; do not silently substitute one for the other. These figures belong to the supplied chart. They are not a full diagnosis of every indoor setup. A useful grow record captures what was measured and when, not merely what a target row said. If something changes, that record helps explain the sequence without relying entirely on memory.
Don’t guess at missing details
When advice is missing, keep the gap visible in your own decision-making. A product name, a photograph or a bottle size cannot confirm an NPK analysis or a dilution rate. Monkey’s supplied information deliberately leaves some details open: Ultra Zyme’s technical instructions and certain size or analysis confirmations. The website hides unconfirmed fields instead of presenting guesswork as a specification. Your stockist can help you obtain the latest confirmed directions. Until then, an honest unanswered question is more useful than a confident invented answer. Likewise, do not assume every supplement should run throughout every week. Root Shoot, Boost, PK 9/18 and Resin each have their own chart windows. Stress has a consistent role through the twelve growth and bloom weeks, but not a listed flush dose. Monkey Mist is a ready-to-use leaf spray, not a reservoir additive with a scaled millilitre instruction. Keeping these jobs distinct helps the system stay simple. If the crop or timetable differs from the chart, describe that difference before asking for a recommendation.
A practical next step for your grow
Start by opening the feeding chart and checking the programme you plan to use. Then read the relevant product page for its description, mechanism, ingredients and confirmed instructions. Safety data sheets are linked where supplied. A safety sheet is valuable for handling information, but should not be treated as a substitute for the feeding programme. Contact Monkey or speak with a stockist if something is unclear. The range was developed by UK growers with 20+ years of combined nutrient-industry experience from our two owners, with more than two years of development and testing before its 2021 launch. The aim is a system that growers can understand, trust and use with confidence, not a bottle for every unexplained problem. Choose a starter or expanded kit around an understood role, retain the correct programme and measure the actual reservoir volume. Keep your notes straightforward enough that you can explain the grow to somebody else. That is science made simple in practice: accurate information, a consistent schedule and no invented shortcuts. UK born. Grower led. Built from experience. Before buying, separate confirmed availability from the product description. There are no published prices in this catalogue, and a size listed for one product is not automatically a size offered for another. Root Shoot sizes require confirmation, while Monkey Mist sizes are not supplied. Ask your stockist about the product and size you actually need. A website photograph can help identify a bottle, but does not override the current verified product information. A good question to Team Monkey includes the product name, whether the grow is in veg or bloom, the medium and the water source. If you are asking about the chart, include the programme and reservoir litres too. Those details make it easier to keep the answer connected to your actual grow. Do not turn advice for a different stage into a new instruction without checking it. The system is intended to stay understandable from start to finish: roots, shoots and fruits, with health-support products used for clear, distinct purposes.
Good questions
What is cal mag?
Cal mag (or calmag) is a calcium and magnesium supplement. Monkey Mag Cal supplies magnesium and calcium with trace elements. Magnesium sits at the centre of chlorophyll and calcium supports cell wall strength.
Why do coco growers use cal mag nutrients?
Coco has a high cation exchange capacity and can bind calcium and magnesium. That is why the Monkey feeding chart calls for Mag Cal when growing in coco.
Do hydro growers need cal mag?
In hydro the nutrient solution is how the plant receives its mineral elements, so your water source matters. Mag Cal is particularly relevant with soft water and RO water; describe your water and system to your stockist.
How much Monkey Mag Cal should I add?
The Monkey Mag Cal dose is 1–2 ml per litre.
Should I add Mag Cal in the flush week?
No. Do not add Mag Cal in the flush week.
Is Mag Cal feeding different in DWC?
No. Feeding is the same in DWC and hydro, with no separate DWC guidance.
What sizes does Monkey Mag Cal come in?
Monkey Mag Cal is listed in 250ml, 1L, 5L and 10L sizes.
