Why did my fertiliser tank go cloudy and clog the drip after I mixed two products?

The cloudiness and white sludge mean the two fertilisers reacted and formed an insoluble precipitate, which then settled out and clogged your emitters. The classic culprit is mixing a calcium-containing fertiliser (like calcium nitrate) together in the same concentrated tank with a phosphate or sulphate source, which forms insoluble calcium compounds. The general rules to avoid this: do not combine calcium sources with phosphates or sulphates in the same concentrated stock tank; keep them in separate tanks if you must use both. Always check compatibility before mixing, dissolve each product fully in enough water, and do a small jar test first by mixing a little of each in a glass and watching for cloudiness or settling before you put them in the main tank. After fertigation, flush the lines with clean water. For your case, separate the incompatible products into different tanks or apply them at different times, and clean out the clogged emitters. Follow the product labels for compatibility, take your KVK or drip agronomist's advice on your fertiliser plan, and keep total doses in line with your soil test without over-applying.