Most spa owners change their hot tub’s water every 2 to 4 months. Over time, salts from sweat and other non-organic materials build up in the water. These Total Dissolved Solids, or TDS, cause cloudiness or other problems.
Even though organic materials like skin cells & bacteria are destroyed by your hot tub shock, TDS levels still increase. But how do you really know when it’s time for draining?
Maintaining your pH, Total Alkalinity, chemicals & filters makes your water last much longer. When the TDS level exceeds about 1500 PPM, it’s time to change the water. These levels can be checked with TDS test strips.
Estimating How Long Between Water Changes
Use your manual to figure out how many gallons are in your spa. Determine the estimated number of days between water changes:
Bather load is the average amount of people in your hot tub per day. More users per day will need more frequent water changes.
- Estimate how many times your spa was used in the last month
- Multiply by number of users
- Divide by 30 days
For example, if you used your spa 15 times last month with yourself and 3 friends:
- 15 times x 4 people = 60
- 60 / 30 days = 2
- That’s an average of 2 people in the spa per day
Time Between Draining
- Divide your total spa gallons by 3
- Divide by the bather load
For example, if you have a 300 gallon spa and our bather load above of 2 people/day:
- 300gal / 3 = 100
- 100 / 2 = 50
That’s 50 days between changes, or about 7 weeks. A larger spa or one with less frequent use will have a longer amount of time between refills.
These are only estimates. We assume that your hot tub water is properly balanced and sanitized.
The cleanliness of your bathers & your local water quality will also affect time between drain intervals. If you shower before using the spa, water will stay cleaner, longer.
Local regulations & ordinances sometimes do not allow frequent water replacement. Many commercial spas are required to drain more frequently due to a high bather load.
Hot Tub Drains
Most spas have a drain faucet, or bib, inside the access panel. A few older or inflatable hot tubs have no drain and have to be emptied with a hose siphon.
Newer spa models feature an external drain, allowing easy draining by attaching a garden hose.
If your spa lacks a drain, or it is difficult to access, consider a draining pump.
Flush Your Spa’s Plumbing with Every Water Change
You do your best to keep your spa clean. What you don’t know is that the INSIDE of your spa’s plumbing system is coated with oily film & contaminants.
Always flush your hot tub plumbing, jets and heater before draining. You will have the cleanest possible water and get more time between refills..