I'm considering starting carbon dosing on my tank. I picked up a bottle of NO3:PO4 -X by Red Sea yesterday and it says to test the nitrate and phosphate levels frequently to adjust the amount of product added to make sure levels don't drop too low. I have seahorses and so I feed frozen mysis at least once per day, which is probably like dumping a spoonful of phosphate in each time. So I'm not sure when would be a good time to test the water. I'm guessing not immediately after feeding, but maybe not right before either?