Draining your spa or hot tub is a very important factor in caring for your spa, the spa's components & more importantly, the people using the spa.
Draining & refilling too often is a waste of your time & the valuable resource of water. Not draining & refilling often enough will lead to hot water care problems which can lead to excessive bacterial growth which can lead to skin rashes, possible ear infections, "hot tub lung" & other physical health related conditions.
Purging, draining & refilling helps to rid your spa of unwanted mold, bacteria & biofilms.
A good tell tale sign that a spa's water needs to be changed is the water is very foamy and the anti-foam you're adding has minimal or no effect and/or the water doesn't smell clean.
When in doubt, drain it out. It may seem like a pain, but your health & safety is our first concern.
The formula is pretty simple. Take the number of gallons in the spa divided by the average daily bather load then divide that number by 3 to get your answer.
First example: a spa or hot tub with 300 gallons of water that is used by 2 people twice each day 5 - 7days (equals bather load of 4). 300 ÷ 4 = 75 ÷ 3 = 25 days or about once per month.
Second example: a spa or hot tub with 300 gallons of water that is used by 2 people once each day 5 - 7days (equals bather load of 2). 300 ÷ 2 = 150 ÷ 3 = 50 days or about once every 2 months.
Why so often? Each person using a spa or hot tub "relieves" themselves of about 1 pint (16 oz) of body fluids per 20 minute soak (sorry to be graphic). Now multiply that by more than one person - as in a party - and the body fluids add up!
This formula is not concrete, HOWEVER it is a good guideline to follow. Depending on how much the spa is used directly determines how often it needs to be drained & refilled. It may seem like a lot but consider this: if you were soaking in a bathtub every night, how often would you drain & refill the tub? Every time you used it, right? Right!
Remember that most commercial spas need to drain & refill their spas at least once per week! Or they should!
Many spa & hot tub water problems start from a lack of proper maintenance; especially drain & refilling. But it's just a little more than that. We are answering a LOT of questions dealing with slime, spa mold (WWM) & biofilms lately.
Keep in mind that these problems are preventable. Also keep in mind that normal maintenance including shocking & water balance will have almost no effect. The fact is shocking with tons of chlorine, bromine or hydrogen peroxide WILL NOT do a good job killing it, never mind removing it.
WWM grows & thrives on an underlying "bed" of bio-film. And even bio-film is VERY chlorine/bromine resistant. The only way to deal with the WWM is to use a product such as Spa Purge (good) or Swirl Away or Spa System Flush or SpaBoss Whirlpool Rinse (all of these are OK) or AquaFinesse Spa Clean Tablet (better) or Hot Tub Serum Total Cleanse (BEST - 10 times better & faster) to attack & remove the biofilm. Here's some further information regarding biofilms & white water mold.
Follow these 3 Steps whenever you Drain & Refill your spa:
In a bad or serious case of WWM, it may be a good idea to repeat the procedure. That way you can start off clean. Biofilms will re-grow, so whenever you drain & refill the spa, you'll need to purge the plumbing lines where all of that stuff grows.
There is no real way to prevent biofilm growth, unless you are supplementing the spa care with AquaFinesse or Hot Tub Serum. These products have good field proof of preventing & removing bio-films.
Chlorine, bromine will both be absorbed by the biofilms. Ionizers like Spa Frog or Nature 2 have no effect. Biguanides like Baqua Spa, Soft Soak or Leisure Time Free will only "adhere" to the bio-film.
There is no easy fix and you've got to be aggressive against it.
Hot Tub Serum Total Cleanse does in a matter of 45 minutes what other products require 12 hours or more to accomplish!
AquaFinesse Spa Clean Puck, the original deep cleaner of biofilms for spas & hot tubs
Hot Tub Serum System spa water care provides initial & continuous deep cleaning of biofilms. Now EPA registered to effectively kill biofilms!
AquaFinesse Hot Water Care System, the original & proven system of treating & removing spa & hot tub biofilms, naturally