{"product_id":"british-minerals-calmag","title":"British Minerals CalMag – Calcium \u0026 Magnesium Supplement","description":"\u003ch2\u003eCorrect Your Water Before It Costs You a Crop\u003c\/h2\u003e\u003cp\u003eBritish Minerals CalMag is a \u003cstrong\u003ehighly concentrated calcium and magnesium supplement\u003c\/strong\u003e made in the UK, built to correct soft, filtered or reverse-osmosis water before it ever reaches the root zone. The declared analysis is \u003cstrong\u003e2.33% calcium (as CaO)\u003c\/strong\u003e and \u003cstrong\u003e1.66% magnesium (as MgO)\u003c\/strong\u003e, held in the ratio plants actually draw the two elements down in, so topping up one does not quietly push out the other.\u003c\/p\u003e\u003cp\u003eIt is a corrective supplement rather than a feed, so it carries \u003cstrong\u003eno NPK\u003c\/strong\u003e and will not disturb the balance of the base nutrient you are already running. It works alongside any feeding programme and suits \u003cstrong\u003ecoco, soil and every hydroponic system\u003c\/strong\u003e, which makes it the one bottle worth keeping on the shelf whatever the grow looks like.\u003c\/p\u003e\u003ch3\u003eKey Benefits\u003c\/h3\u003e\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003e2.33% calcium and 1.66% magnesium\u003c\/strong\u003e in a balanced, immediately available form\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eCorrects soft, filtered and RO water\u003c\/strong\u003e that carries almost no calcium or magnesium of its own\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003ePrevents the two most common deficiencies\u003c\/strong\u003e seen in coco and under high-output LED lighting\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eHighly concentrated\u003c\/strong\u003e - a dose of 0.5-1ml per litre is enough for most tap-water setups\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eNo NPK\u003c\/strong\u003e, so it will not skew the ratio of your base feed\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eSuits every medium\u003c\/strong\u003e - coco, soil, clay pebbles, rockwool and recirculating systems\u003c\/li\u003e\n\u003c\/ul\u003e\u003ch3\u003eRusty Leaf Spotting and Yellowing Between the Veins\u003c\/h3\u003e\u003cp\u003eBrown speckling on new growth and yellowing between the leaf veins are almost always a calcium or magnesium shortfall rather than anything wrong with the feed itself. Coco holds onto calcium and releases it slowly, RO and softened water arrive carrying next to none, and modern LED lighting drives the plant hard enough that it burns through both faster than a base nutrient alone can replace them. Correcting the water at the reservoir - before the plant ever shows a symptom - is far quicker than trying to rescue leaves that have already been marked.\u003c\/p\u003e\u003ch3\u003eHow to Use\u003c\/h3\u003e\u003cul\u003e\n\u003cli\u003e\u003cstrong\u003eShake well before use\u003c\/strong\u003e\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eAll media and systems:\u003c\/strong\u003e \u003cstrong\u003e0.5-1ml per litre\u003c\/strong\u003e of water\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eTiming:\u003c\/strong\u003e from \u003cstrong\u003eearly vegetative growth (week 3) through to late flowering\u003c\/strong\u003e\n\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eAdd to the reservoir first\u003c\/strong\u003e and mix thoroughly before the rest of the feed goes in\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eCheck EC and pH after adding\u003c\/strong\u003e and adjust to your target\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eDo not exceed the stated rate\u003c\/strong\u003e - excess calcium locks out other elements\u003c\/li\u003e\n\u003c\/ul\u003e\u003ch3\u003eTechnical Specifications\u003c\/h3\u003e\u003cdiv class=\"hcs-specs\"\u003e\u003cul\u003e\n\u003cli\u003eType: calcium and magnesium supplement\u003c\/li\u003e\n\u003cli\u003eCalcium: 2.33% w\/v (as CaO)\u003c\/li\u003e\n\u003cli\u003eMagnesium: 1.66% w\/v (as MgO)\u003c\/li\u003e\n\u003cli\u003eNPK: none declared - this is a supplement, not a base feed\u003c\/li\u003e\n\u003cli\u003eDose rate: 0.5-1ml per litre of water\u003c\/li\u003e\n\u003cli\u003eTiming: early vegetative growth through to late flowering\u003c\/li\u003e\n\u003cli\u003eSuitable for: coco, soil, rockwool, clay pebbles and all hydroponic systems\u003c\/li\u003e\n\u003cli\u003eManufactured in the United Kingdom\u003c\/li\u003e\n\u003c\/ul\u003e\u003c\/div\u003e","brand":"British Minerals","offers":[{"title":"1L","offer_id":53505606222090,"sku":"BM-CAL-1L","price":14.9,"currency_code":"GBP","in_stock":true},{"title":"5L","offer_id":53505606254858,"sku":"BM-CAL-5L","price":49.9,"currency_code":"GBP","in_stock":true},{"title":"25L","offer_id":53505606287626,"sku":"BM-CAL-25L","price":199.9,"currency_code":"GBP","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0748\/7127\/5786\/files\/CALMAG__1.png?v=1786478482","url":"https:\/\/hydrocropshop.co.uk\/products\/british-minerals-calmag","provider":"Hydro Crop Shop","version":"1.0","type":"link"}