Sometimes my deep fried fish turns out very crispy and sometimes not and I don't know why. I generally make my batter with AP Flour, salt, baking powder and a sparkling liquid, either seltzer or beer. I mix it up ten minutes or so before using it. I put the fish (usually cod) in milk, then flour and finally into the batter. I deep fry around 365 F.How can I get consistently crispy fish? Some batter recipes include eggs, or a mixture of flour and cornstarch. Will these ingredients increase crispiness? Is temperature control of the batter crucial?