Remove carbon, phosphate removing media and any other chemical media like Purigen or so, also turn off Ozonation and UV if you have them. Keep all reactors running and all water in the system in circulation so you reach all places in the system. Keep the skimmer running but plug the air so you have water circulation inside but no skimming.
The original treatment called for six hours, now recent evaluation show that you need at least 8 hours 12 being the best.
Once the period pass you need to make as large a water change as you can minimum 20 to 25%, replace new carbon twice the usual amount, (the more the better). Open the skimmer air, turn UV and Ozone on as well as all other chemical media.
Repeat the treatment three more times after one week, after two weeks and after a month.