Coolant or Distilled Water for water cooling

Distilled or Deionized water is basically the best thing you can hope for. Everything they advertise about coolant is very misleading.

Non-Conductive - Yes coolant may be less conductive than distilled water but pure water is actually a very poor conductor. What conducts electricity is the dissolved ions in the water. No matter how pure the water or coolant may be, anything will gains ions very quickly and become very conductive from contact with the metal blocks.

Corrosion inhibition - Galvanic corrosion happens when conflicting metals are mixed together and redox reactions happens. However in this day and age of watercooling you can't find aluminum or stainless steel waterblocks anymore. Usually everything is copper or nickle plated copper and using these two metals will not cause galvanic corrosion. Having corrosion inhibitors actually do nothing.

Better performance - Basically water is the best thing you can use. The random stuff they add is never a better heat conductor than water. Whatever tests they publish is probably cherry picked just to support their claims.

Algae inhibiting - Algae growth can be prevented by a silver coil. However algae growth probably won't happen anyway if you don't contaminate your equipment with tap water or expose your loop to direct sunlight. I personally never had algae growth despite never using any preventive measures.

Now drawbacks of coolant. Yes! they have drawbacks and I bet you didn't think about that.

Stains and residue - Colored liquids will stain tubes, your hands, and anything you spill it on. While all coolant even the colorless ones will leave some powdery residue when dried. Imagine what happens when you spill it on your motherboard or in your case. You need to rinse that stuff good.

Coolant dries slower - most coolant is basically a glycol solution. A drop of liquid will not dry for days and can become conductive really quickly when exposed to metals and dust. I personally got screwed over when some liquid I spilled 3 days ago shorted my entire system. I cleaned it as best as I could and left it to dry for 3 days just in case. Basically the non-conductive fluid and blah blah blah whatever they try to upsell me didn't do a damn thing.