Watercare 101

Here at Robertson Spas & Hot Tubs, our goal is to make owning and maintaining a hot tub as easy as possible for the clients we serve at our three locations in Tampa, Clearwater & Sarasota Florida.  This is blog is going to focus on the absolute most important and basic tenants of water care for your home spa.  I will be glossing over some details in the interest of keeping hot tub water care as simple as possible.

1. Test the water.  Do not go to a pool supply place with a cup of hot tub water.  You’ll end up buying a couple hundred dollars worth of chemicals and leave more confused than when you got in there.  All you need are basic hot tub test strips that read chlorine, ph and/or alk, and overall water hardness.  There are many more things you can test for in the water, like iron, phosphates, tannins, or Sulphur.  Although these can affect water clarity, the amount of chlorine you’re using in your spa or other aesthetic issues, generally things like phosphates or tannins are not going to hurt the life of your hot tub or create an unsafe environment.

2. Check results, all you have to do is match the colors on the hot tub spa test strip to the bottle.  You only have about 30 seconds to get a good read, so make sure to take note of all the levels, because you won’t be able to check the strip again later.

3. Sterilize the water.  If you just filled your spa, your chlorine will be reading 0.  The best most simple hot tub sterilizer is going to be chlorine.  For new users, on a fresh fill, it’s always best to start with a bottle of Hot Tub rated, granular chlorine.  The standard amount to add is ½tsp per 100 gallons, but always read your bottle to make sure.  Once you add the chlorine, turn on the jets or a clean cycle.  It usually takes about 45 minutes to mix in, if the water is over 80 degrees.  Colder water will take longer.

4. Balance the acidity of the hot tub water.  Acidity is represented as Ph/Alk on your test strip.  If the number is high, your water isn’t acidic enough, if it’s low the hot tub water is too acidic.  Even though Ph/Alk will often have separate test colors, they can only be adjusted in tandem.  Sometimes one may be too high and the other too low, and you may have to split the difference between them, and that’s fine.  The acidity is a little too high or low is not a big issue in the short term for your hot tub.  So there isn’t a point in burning through 10 test strips and spending 2 hours adjusting the hot tub water If it reads a little high add some ph/alk down, if it’s too low add some ph/alk up.  The bottle will tell you how much to add, I usually just add a single teaspoon on small tubs, and a tablespoon on larger 7×7 tubs.  You can check the Ph/Alk again next time you test your chlorine levels, and adjust it a little each time.  DO NOT ADJUST THE PH/ALK UNTIL THE CHLORINE IS MIXED IN THE WATER, its never a good idea to add hot tub chemicals “on top” of each other, you want to give them time to mix up in the spa first.

5. Check the hardness, generally hardness isn’t an issue out of the hose, for chlorine water care, but it does need to be monitored in the same way as ph/alk.  It won’t be a problem if it’s a little too high or low for a couple of weeks, but if you don’t monitor it over the course of a year having it out of range can cause issues for the hot tub.  It’s much easier to increase hardness than decrease it, so I will be writing a separate blog just for hardness issues in a hot tub.  To increase hardness just add liquid calcium If it’s too high out of the hose, which is very rare, even if you think your water is tough, it’s likely not too hard for a hot tub to handle.  To decrease the hardness of the hose a portable water softener is required.

6. Your hot tub will be ready to use 45 minutes after you put in the last hot tub water care product.


7. Repeat these instructions 2 days later.   You won’t have to check it every two days forever, on new or used hot tubs, there is likely some algae buildup in the pipes, and it takes some time for the hot tub to sterilize and the chlorine to level off, once it running good you may only have once a week.  In two days if the chlorine is zero add the full dose again and check again in two days, bump your acidity when you check your chlorine.


8. Clean the filter or filters.  This only needs to be done once a month in most cases, simply remove the filter or filters, hose them out really well, and maybe after 6 months use some filter cleaner, and get a new filter every year to 18 months.


There is no way to know exactly how much or how often you’re going to need to chlorinate or adjust the water chemistry.  Everyone uses their hot tub differently, so even if you have the same tub as a neighbor, you may go through more or less chlorine depending on how you use the hot tub.  For example, a single person who gets in the hot tub after they shower uses the spa 3 days a week and keeps their water at 80 degrees, and only heats it briefly before they get in, isn’t going to go through much chlorine.  If you take the same spa, keep it at 104, and have it used by two children 5 days a week that get in and out between doing laps in the yard, the same tub will burn through easily twice the chlorine that the single person.  Keep that in mind, and know that once you get used to taking care of your water, and if you use the tub consistently, you have a good shot of eventually being able to only worry about testing the water once a month.  You may eventually just know when and how much chlorine to add, and you only need to rarely test to make sure your acidity and hardness haven’t gotten out of whack,


There are a lot of tips, tricks, and troubleshooting things I skipped in this post in the interest of keeping this simple.  But following these simple instructions is going to give you a safe, and stable hot tub water experience.  If your hot tub is not green, it’s safe to get in.  If your ph/alk and hardness are in line your hot tub or swim spa will be far less likely to have issues down the road and it will maximize the life of your shell, glues, and components.


It can seem overwhelming if you’re inexperienced, but it’s as simple as having spa-grade test strips, chlorine, ph/alk up & down, as well as hardness up and down.  Test the water, chlorinate the water, slowly adjust the ph/alk & hardness, and repeat every couple of days, eventually youll only will be messing with it once a week or less.


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