In another thread I explained how to use PH up and PH down.
You alway's need to dilute PH products with water before you put into a rez. I recomend 10 parts water to 1 part PH up or down.
If you dump PH solution straight into the res without diluting it, most likely you will have nutrient fallout. Which is what you have, when a res get's cloudy from adding nutes and PH, you messed up. You need to dump the res, start with fresh water filled half way, dump part A, fill up with more water, dump part B in, fill with more water. Then you can put your other nutes in. After all that is mixed up well and settled you can now ad you PH solution slowly.
You need to dilute it, then ad the PH solution VERY SLOW, it should take you about a hour to adjust it properly. You need to put the PH solution in steps, put a little bit in, mix well, wait and do again.
A cloudy res is a Nurient Fallout and is garbage. The main step in this is diluting PH and putting it in the res slowly.