Hot Tub Water Changing

Why and how often is it necessary to change hot tub water?

Regular draining and refilling is a normal part of hot tub maintenance.  Over time the water in the spa absorbs minerals, chemicals and other soluble materials.  The Total Dissolved Solids (TDS) level increases and the water starts to look dull and lifeless.  The water might start to foam. The sanitising chemicals also start to loose their efficiency because of the higher workload placed on them.

As a general guide the following formula can be used to determine how often the spa should be drained:

litres of spa water ÷ average number of 20 minute bathing session per day ÷ 12 = days between draining and refilling.

However, common sense should prevail and obviously you should change your water if it looks dirty, smells or is excessively foamy.

The way in which you maintain your water and clean your filters in between changes will have a significant affect on the frequency of water changes required.

How to change the water and clean your tub

  • A spa with clean plumbing results in cleaner, clearer, fresher water and better circulation, so you should use a spa flush before every water change to remove oils, bio-film and other deposits. Add the flush product to your old water and run your pumps on high speed for about 20 minutes (or overnight at low speed for an even deeper clean). If your spa hasn't been cleaned for a while this will probably flush a lot of muck into your water which you can then throw out with the old water.
  • To drain your spa you can either attach a garden hose to the bottom drain (assuming that you have one on your tub) and wait for it to empty, which will probably take several hours. To speed things up considerably, you can use a submersible pump.
  • Once your tub is empty you should clean the shell with a specialist, non-foaming surface cleaner and a non-abrasive pad. Household cleaners will introduce chemicals into your water that will be unpleasant and even dangerous to bathe in and will cause havoc with your water balance and foaming. Rinse as much of the cleaner as possible away after use.
  • We recommend that you clean your cover at least at every water change.
  • Always thoroughly clean or replace your filters at each water change.
  • Refill with fresh water.
  • Test and balance the water as required for your chosen sanitizer.
  • Apply a shock treatment to remove any contaminants in the source water.
  • Re-apply your chosen sanitiser.
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