{"product_id":"hanna-groline-ph-4-01-calibration-buffer-230-ml","title":"Hanna GroLine pH 4.01 Calibration Buffer — 230 mL","description":"\u003cp\u003epH 4.01 is the acidic calibration point used to set the slope in a two-point calibration — essential for accurate readings in the 5.5–6.5 range most nutrient solutions run at. The 230 mL bottle is the right size for smaller grows.\u003c\/p\u003e\n\u003cp\u003eHanna calibration buffers are prepared to precise formulas and standardized against NIST-traceable reference standards, so your meter reads true every time you calibrate. Each container is airtight with a tamper-proof seal, and the lot number and expiration date are printed on the label. Unopened, Hanna buffers carry a 5-year shelf life.\u003c\/p\u003e","brand":"Hanna Instruments","offers":[{"title":"Default Title","offer_id":54278740574491,"sku":"HI7004M","price":21.99,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0708\/6768\/1563\/files\/hi7004m_59dbe5c0-56c4-409b-b711-6c479b91608c.webp?v=1792257202","url":"https:\/\/ghhydro.com\/products\/hanna-groline-ph-4-01-calibration-buffer-230-ml","provider":"Green Harvest Hydroponics","version":"1.0","type":"link"}