I had foam when I first ran my WC loop after putting in 10% antifreeze addative. I just ran it overnight, and when I woke up the foam was gone and everything was running smoothly. The foam just bled out like air bubbles do, just a little slower. If after a while of running it you still have foam, then try changing out your water with more distilled water, or use a different coolant, you might have had a bad reaction. But more than likley it will go away after a while.
thanks for the rreplies guys, i use the hydrx coolant + distilled water.
The foam is now gone, i added more distilled water, b/c i think i put too much coolant.
So, everyhting is okay. I opened up my reservoir to get let some air out.