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How long after purging with SC-1000 will a pool be able to hold chlorine?

The SC-1000 purge dose depletes chlorine for a few days while it finds metals and minerals to chelate.

It usually takes 2-3 days before being able to hold a free chlorine level after purging with SC-1000. The length of time depends on:

  • the water temperature,
  • the amount of metals/minerals in the water,
  • the pool's circulation/turnover rate, and
  • the amount of SC-1000 added.

Water temperature

The warmer the water, the better and faster SC-1000 does its job. Cold water slows chemistry down, and SC-1000 is no different. Chelation takes time. Water below 70ºF can take a week or more to hold chlorine again. Water about 75-80ºF should take 3-4 days.  Water over 80ºF generally takes 2-3 days. 

This, of course, can be accelerated if you are adding calcium chloride to the pool. If so, pre-chelate the calcium chloride by adding the SC-1000 to the bucket (or Orenda Startup Barrel™) with dissolving calcium chloride. The heat from dissolving calcium activates SC-1000, and accelerates it doing its job in the water.

You can also turn on your pool heater to accelerate SC-1000 chelation.

Amount of metals/minerals in the water

If there are high levels of metals in the water, SC-1000 has plenty to do, and it will do its job relatively quickly. Higher levels of calcium hardness also help.

Pool circulation/turnover rate

The better the circulation, the faster SC-1000 can spread and do its job. This translates to less time before holding chlorine again. 

The amount of SC-1000 added

You might be surprised, but one of the more common issues we hear about is people overdosing SC-1000.  Don't do that. Follow the dosing in the Orenda app, and follow the instructions on how to use SC-1000. With the exception of a startup, rounding up on SC-1000 just means more time before holding chlorine again.

One thing we recommend is dividing up the purge dose of SC-1000 into multiple visits.  Maybe do 1/3 or 1/4 of the dose at a time, separated by a few days. Getting SC-1000 into the pool is not a race (except on a startup, when it needs to all be added as the pool is filling).

Why does SC-1000 wipe out free chlorine?

We cover this question more in-depth in another article. In oversimplified terms, SC-1000 is immune to chlorine oxidation, but chlorine does not know what SC-1000 is. So chlorine tries to oxidize SC-1000 (and fails), and it gets reduced. In other words, chlorine is wiped out quickly because it gets used up trying to oxidize SC-1000.

SC-1000 will eventually chelate metals and minerals, which changes its valence so that chlorine no longer tries to oxidize it. Chlorine and chelated metals live in harmony at that point.

SC-1000 updated bottles