As far as the grain strike, I use beersmiths infusion temp tool. It seems to hit it right on, if you have a RIMS set-up how is your heat regulated? Manually? If so the pronged thermometers need calibrated from time to time. A high quality thermocouple is an investment, but a lifetime investment. Or invest in a heat regulator, that has a in line T probe thermostat and it will keep your coldest temp at a +/-1F of your target. It's also a bigger investment, but much like a mill can make all the difference in your final product. And if you can put a ball valve on each side of your pump you can help slow things up. Open them up all the way, turn your pump on, slowly turn your flow in down and flow out down little by little until you see the flow you want in your recirculation. That should be the same speed as your sparging I believe.
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