Yes, I mixed some 2-3 cups of starter with 3l and ended up with a 2.54 pH indeed.
I"m testing with a phmeter I found on amazon (This kind) that served me well so far and was tested 4 or 5 batches ago with the powders it came with.
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I've justed tested on apple cider and it displayed 2.34 and with lemon juice, 1.3.