What Newdude is saying regarding not having to drain after a “purge cycle” is correct. For very highly contaminated hot tubs or tubs that have been drained for the off season and then refilled for use, you may want to practice a procedure that is highly effective, without using an ocean of water for successive purges. Here is what you do. Let’s base the purge on a typical 400 gallon hot tub. After removing the filter(s), headrests and pillows and placing the filter(s) into the hot tub proper, add 3-4 LEVEL TEASPOONS of Ahh-Some Gel into the FILLED tub. It is ok if the water is not hot. The product is as effective in any temperature water but warm or hot water dissolves the gel faster. Ideally, your hot tub has a residual of a sanitizer in the water at the time of the purge. We want to be sure to kill any organic animate bacteria we will be really ticking off during the purge process. Note also that some filters, especially the pleated paper disposable filters should NOT be placed into the tub while purging. The same thing may be true for ceramic filters (Watkins). Always wear latex gloves and wear eye protection. It is not just for the chemical contact issues but it is for the biofilm issues as well. This released stuff can harbors a wide array of bacteria. Turn the jets on high for 10-15 minutes. You will see foam and this is good. Turn the high speed pump on and off intermittently a few times to possible blow any hanging chads of biofilm from the colonized slimy gunk in the plumbing. WIPE and of the peanut buttery sticky stuff you see around the waterline and especially in the filter housing area where the suction is strongest. The foaming will now go down since the turbulence has subsided. Using the same water that you added the first dose of Ahh-Some to, add 2 more LEVEL TEASPOONS of gel to the tub. Run the high jets for 5-10 minutes. Shut off pumps. Wipe any released sticky colorful gunk with a wet towel. Very important to wipe ALL the gunk you may see at the waterline. Let the hot tub set overnight with the pumps OFF.
No activity at all. Just shut it down. Note: It may be helpful to turn the high pump on periodically for a minute or so during the shutdown. WIPE and new residual sticky gooey stuff that may have been released. Next day, add 1 additional LEVEL TEASPOON to the same water. Run the jets for 5 more minutes. Drain the hot tub using the gravity drain at the hot tub base or hasten the drain by using a submersible pump. Hose and rinse the shell as the water drains to eliminate any sticky stuff. Wipe the shell clean. Add water to the tub always making sure that you place the hose into the skimmer (filter) area. This will eliminate any chance of a “dry fire” in the heating element and allow the pump(s) to pick up a prime without having any air in line issues. Hopefully, your filter(s) are clean and dry so you can place them back into service. So, you have used the same water for 3 purges. We recommend that you NEVER leave a hot tub empty for an extended period of time. We also recommend that you always have adequate sanitizer in the vessel at all times, not just when you are soaking. We strongly recommend that you ditch the test strips and get yourself a reliable test kit. Sorry for the long post but this is important If you want to enjoy the clearest and healthiest hot tub water ever.