@wintermute - This thread has been extraordinarily valuable, thank you for all of the information! I have a few follow-up questions now that you've had this setup for over a year.

  1. Are you still relying solely on H2O2 for sanitation? How often do you change your water and filters?
  2. If you added an additional sanitation option, would you go with ozone or UV? Based on my informal research, 66% of commercial cold plunges rely on ozone, (+ spa chemicals) 16% on UV, (+ spa chemicals) and 16% on spa chemicals alone.
  3. If you went with ozone, would you 1. use a JED 303 and drill a hole in the cooler lid, or 2. install inline with a venturi injector?
  4. Why did you go with a 4.5" filter housing vs. the cheaper 2.5" filter housing?
  5. Why did you use PVC fittings instead of barbed hose fittings + clamps?
  6. The Grizzly 450 has two drain holes, one on either side of the cooler. Would you recommend using both of these existing holes for supply/return, or still drilling a hole higher up on the cooler wall and installing a bulkhead?

    dastratman

    Yes H202 is fine, change water every 2 months max and filter almost never. If I didn't use H202 I would use small amounts of chlorine. I wouldn't use ozone or UV because I don't see any need and just added cost and complexity. If I was forced to use ozone I might inline it but either option is valid and I would spend too much time debating. Bigger filter housing bigger flow rate. Barbs and clamps are fine if that's your style don't let anyone stop you. If I had a 450 I would still drill a bulkhead to keep the connections on one side and I want the water input line to be higher than the drain line.