How to use SPA-500

SPA-500 is a pre-drain hot tub scrub, designed to remove organics and other contaminants within the spa system before draining, rinsing, and refilling.




SPA-500 Pre-Drain Spa Scrub is our concentrated spa system cleaner. It is CV-600 based, but with additives that make it much stronger for concentrated cleaning of plumbing systems. This procedure covers dosing, directions for use, and best practices.

Related: How to Implement the Orenda Program

You may need:

  • A garden hose (to rinse out the spa system's pipes)
  • A clock or stopwatch (if you don't want to estimate 5-10 minutes)

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SPA-500 dosing

With SPA-500, round the dose up to the nearest eight-ounce (8 fl.oz.) quantity. Eight ounces treats 500 gallons. So if you have an 800-gallon spa, round up and use two bottles (16 fl.oz. total).

Spa/Hot Tub volume SPA-500 Dose
up to 500 gallons (1893 L) 8 fl.oz. (237 mL)
501-1000 gallons (up to 3785 L) 16 fl.oz. (0.47 L)


How to use SPA-500

Follow the instructions on the back of the bottle. Here they are:



SPA-500 is only to be used prior to draining and refilling. There is no weekly maintenance dosing.

  1. Shake the bottle well before use.
  2. Remove filter cartridge from the spa and clean separately.
  3. Turn on the spa circulation and jets.
  4. Pour SPA-500 anywhere in the water (8 fl.oz./500 gallons).
  5. (ON) Run spa with all jets and blowers on for 5-10 minutes.
  6. (OFF) Shut off the system and keep it off for 5-10 minutes.
  7. (ON) After being shut off for 5-10 minutes, run the system again for 5-10 minutes.
  8. (DRAIN) After 5-10 minutes of running, shut off the system and drain the spa completely.
  9. (RINSE) Thoroughly rinse with fresh water, including running a water hose through the skimmer/suction line.
  10. After the spa is completely drained and rinsed:
    1. Reinstall the cleaned filter.
    2. (REFILL) Refill with fresh water.
    3. Adjust water chemistry to the spa manufacturer's specifications (The Orenda 
      App can help!).


Best practices

  • When in doubt, rinse it out. More rinsing is never a bad idea. If you're not sure you have given it enough time to flush water through the suction line, then keep flushing.
  • Run it longer if you want to. The second run of the pipes (step 7 in the directions) can be as long as you need it to be. We say 5-10 minutes, but if you wanted 15-20 minutes you could. Just be aware that there could be heavy foaming.
  • Never add SPA-500 when people are in the water. While SPA-500 is NSF-50 certified, that certification is for when the product is used as directed. The directions clearly say "Do not use with bathers in the water" for a reason. This is a strong chemical. Keep out of reach of children.
  • Round up to the nearest 8 oz. dose. Unlike most Orenda products, SPA-500 does not need a measuring cup. Just use it in 8 oz. increments, and always round up if you're not sure. It's going to be drained anyway.