Right now I'm running a secondary loop with Motul Mocool. Don't have Glycol because is homologated for racing but has corrosion inhibitor. For the moment I didn't notice any problem with it and is very cheap
Peak High Performance. I don't know they all have quite a bit of additives. But I would use very little...some of the seal material doesn't like some of that stuff. Meant more for the more rubber and oring like variations.
Haven't seen it foam when in use, although when you shake it to mix with the water in the first place it definitely makes some bubbles at the top for a quick second then settles down... ready to pour in after that and stays nice and calm.
Well it's Cheap Loop in General...you have a 20-100$ Block. 1/2-5/8 food grade flex. The 240mm or optional 360mm. A Pump can run you a few dollars. No I'm not Worried about it. Run Glychol. that kinda hose is tolerant to other stuff though too. 3-5% and Preferably Distilled. The Glychol does slow down that Scum and corrosion.