It doesn’t take long for spa water to go south when the hot tub has been sitting for days or weeks without being filtered or sanitized. How long? In moderate temperatures, spa water can stay fresh for up to two weeks, if covered tightly.
Spa water that sits longer than a week or two will begin to grow algae and bacteria, even without light, under a dark spa cover. Spas that sit untended will begin to grow biofilm or bacterial colonies – the kind of scum you see in a toilet that hasn’t been used or cleaned in awhile (sorry for that analogy!).
For spas and hot tubs that have been sitting, unused and unmaintained, for a period of longer than a few weeks – here’s the process to bring it back online.
TEST FILTER SYSTEM
Before you do a lot of work cleaning the hot tub, make sure that the spa pump and filter are operational. Add water if needed to bring the level up to mid-skimmer, covering the spa filter, which may need to be replaced with a new filter cartridge.
Turn on power at the circuit breaker, then open up the spa cabinet to find the spa equipment. Reset any popped GFCI outlets, and power up the spa pack. Check that all valves are open, before and after the pump, and take a good look for any leaking water under the spa.
Using the spa side control, run the spa pump on low speed and high speed briefly, which will help dislodge gunk in the pipes. Some spas have two pumps, a circulation pump and a jet pump; test them both to be sure that they will be operational after you drain & clean the hot tub.
DRAIN & CLEAN
Draining the spa is the best way to clean a hot tub that has been sitting for awhile. If your water is in fair condition, hazy but without visible algae or biofilm growth, skip ahead to the next step and purge the plumbing, to clean a hot tub without draining.
To drain a spa or hot tub, look for the drainage port or hose. Some spas have a small access port at the base of the cabinet to drain water. If not you will usually find a short hose or a hose connection at the lowest point of the spa. Pull out the hose, or connect a hose, and let the water drain by gravity. You can also use a submersible pump to drain a spa. Be sure that the power to the spa is OFF before draining.
As the spa is draining, if the water condition is really bad, use a garden hose to spray off the spa surfaces. You can also spray into the skimmer, or spray water directly into the spa jets, to help loosen slimy gunk. Just be careful not to spray the spa pack, or spa equipment (pump, filter, heater).
REFILL & PURGE
Now that you’ve removed the funky, gunky water from the hot tub (or if you want to clean a hot tub without draining), the next step is to purge the spa, which means to add a chemical that will remove the slimy biofilm that lines the inside of the pipes, and has made a home in various nooks and crannies in the spa air and water plumbing.
You can use Natural Chemistry’s Spa Purge, or Leisure Time’s Jet Clean. Follow label directions, adding it to the spa with the pump system running. In a very short time, you will notice the funk and gunk rising to the surface, as a brown foam. Turn on the jet pump and blower to help dislodge any remaining bacterial colonies.
DRAIN & REFILL
Drain the spa again, using a hose or rag to remove the scum around the top of the spa, cleaning as the water level drops. When completely empty, use sponges or a wet/dry vac to suck up the last bits of water.
One more time to the well! Refill your spa with fresh water. When full, test the water chemistry and add adjustment chemicals if needed to balance the pH, alkalinity and calcium hardness. Add a bromine booster (if you use bromine tabs), and then shock the hot tub with 1-3 tablespoons of spa shock, following label instructions.
A new spa filter may also be in order, to keep the hot tub water clean and clear. Replace your spa filters every 18 months, or every 12 cleanings, whichever comes first.
Happy Hot Tubbin’
Hot Tub Works