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keeping your hot tub (spa) clean

Sometimes dealing with the chemicals that are required to keep your hot tub water clean and balanced can be confusing. Here's a little information that may help clarify the things you can do to enjoy your hot tub in a safe and healthy way.


pH is the single most important element in hot tub water chemistry. It affects every other chemical balance in hot tub water.

what is pH?

Water pH is a measurement of the concentration of hydrogen ions in your hot tub water. Without getting into a chemistry lesson, let's just say that pH is important because if you don't keep the pH levels within a small range (7.2-7.8), your water can become too alkaline (base) or too acidic (acid). If your pH is too low (less than 7.2), the water is too acidic and it can corrode parts of your hot tub and irritate parts of yourself (like your skin and eyes). If your water is above 7.8, it is too alkaline which can cause "scaling" from minerals and metals in your water forming deposits and possibly stains on your hot tub's acrylic surface. So, how do you know if your pH is in the right zone? You test your water using a test strip. Then, use pH additives to achieve the right pH balance. We sell a product line from Leisure Time with products that can raise pH called "SPA UP" or lower it with "SPA DOWN", easy to remember!


Alkalinity is the second most important item to watch. Total alkalinity refers to the ability of the water to resist changes in pH. Controlling alkalinity can help keep your pH in the appropriate range thereby reducing the need for pH balancing. If your test strip indicates it is high, you can lower alkalinity using a pH reducer such as the Leisure Time "SPA Down". Or, if you need to raise alkalinity, you can use an alkalinity increaser. We have an enhancement called "Alkalinity Increaser". The name says it all. And finally, "SPA Up" raises both pH and Alkalinity together.


Sanitizers kill the bacteria that can grow in warm water. Sanitizers, also referred to as disinfectants, are the primary defense against water that is unsafe and unhealthy for us to be in. As such, it is the next most important item to test for in your spa water.

Chlorine: You're probably familiar with chlorine as the primary sanitizer used in pools. Chlorine can be used in a different concentration in hot tubs. There are chlorine tablets and chlorine granules created specifically for hot tub use. There are some slight disadvantages to using chlorine in hot tubs; primarily it is not stable at the high temperatures found in most hot tubs, where as bromine is not so affected.

Bromine: Bromine can be added to a hot tub in the form of tablets, nuggets or granules. One form is sodium bromide, which needs to be activated with an oxidizer such as chlorine or Potassium Monopersulfate (non-Chlorine) shock. Many people choose bromine over chlorine because bromine is an effective sanitizer in hot tubs as it doesn’t “gas off” at temperatures higher than 98 degrees and produces fewer odors than chlorine. Bromine works in a wide range of pH levels. Bromine is generally distributed through a floating feeder or cartridge system.

Biguanide: Biguanide (bi-gwan-eyed) sanitizers are a non-chlorine, non-bromine product that kills bacteria by attacking the cell wall. The elimination of organics is accomplished with a hydrogen peroxide-based oxidizer used to “burn” off the organic matter and keep the water clear. This system produces fewer odors than chlorine or bromine and does not “gas off” at spa temperatures.

Ozone: Ozone is an oxidizer and not a sanitizer, but it reduces the work of the sanitizers and lowers the level of sanitizers needed in the spa to keep it clean. The ozone process requires that your hot tub is equipped with a piece of equipment called an “ozonator.” Even if you have an ozonator, you will need to supplement your water with a low level of sanitizer like bromine or chlorine. (Don't let anyone tell you otherwise. The idea that a hot tub can be thoroughly sanitized with ozone alone is a myth.) Ozone is compatible with bromine, chlorine, biguanide and mineral systems.

Mineral Sanitizers: You can use mineral systems to assist, but not entirely replace, your sanitizers in keeping your hot tub clear of contamination. Mineral cartridges are typically placed inside your filter cartridge or are contained in a floating dispenser through which the sanitizing minerals are slowly released into the water over time. Many people prefer to use mineral sanitizers because of the lower levels of chlorine or bromine. It is necessary however, to augment their use with oxidizers such as Potassium Monopersulfate (MPS) to keep your water clear and fresh.

Important: The use of any sanitization system requires the use of test kits or test strips. We like test strips because they are simple and easy and offer adquate accuracy in testing home pool and spa water. Because they are easy to use, it is more likely that the home owner is going to test more frequently to insure the water is balanced and being sanitized. However, kits with test solutions (drops) that measure the amounts of various sanitizers, calcium, pH, alkalinity are valuable testing products. Public swimming pools will not allow test strips to be used to test water based on the theory that the solution testing (known as DPD) is more accurate. Because of the somewhat more complex methods used, they require more time and understanding from the home owner.

changing your spa water

The common recommendation is to CHANGE SPA WATER about every 3 months depending on the amount of use of your hot tub. No amount of chemical additives can protect you completely in water that is old and dirty. Changing water is a simple task and your family and guests will be glad you did. The high temperatures sustained in hot tubs and their relative small size create an environent that is more subject to contamination that larger pools of water at lower temperatures. It is also important to keep your filter system clean and operational.

other important stuff

Shock Oxidizers: A very useful product that oxidizes the bacteria and helps to get rid of organic matter like dead skin, skin oils, cosmetics and lotions. What happens is the bacteria and other organisims are killed by the sanitizer and then the oxidizer 'burns' the leftover organics by chemically breaking them down into nitrous and sodium gases, which is released from the water at the surface. Not a savory picture, but the alternative result of no sanitization or oxidization is not very appealing either!

There are two types of shock, non-chlorine shock and chlorine shock. Both work as a good maintenance product to oxidize your spa. An advantage to Non-chlorine shock such as Potassium Monopersulfate (MPS) is that it allows you to get back in the hot tub 15 minutes after treatment. Chorine type shocks usually require quite a bit more time for the water to return to normal use range.

For fresh water fills, use a chlorine shock. Chlorine shock is a sanitizer and will leave chlorine residual, which is critical to a clean, safe spa. A non-chlorine shock works great once you have an established a residual of chlorine or bromine in the spa as it can oxidize organics in the water without increasing your sanitizer residual. It also allows you to use the spa soon after treatment. Be sure to follow chemical manufacturers’ instructions for proper use.

Neither chlorine nor non-chlorine shocks are compatible with a biguanide system. The biguanide system uses a hydrogen peroxide oxidizer to eliminate organics and does not require shocking to maintain sanitizer efficiency.

Calcium Hardness: If you live in an area with particularly “hard” or “soft” water, it's worth checking your water calcium levels with your test strip and adjusting them if necessary. You can adjust your calcium levels up with a calcium increaser for water that is low in calcium. If the calcium level is too high you can adjust the pH and alkalinity to their lower ranges to help avoid cloudy water and scale.

Heavy Metals: Some local water contains unusual amounts of iron or copper. A greenish tint in your water may indicate the presence of these metals. If this is the case in your area, resist the temptation to file for mining rights. These pesky metals can, among other things, stain your hot tub shell, increase your sanitizer consumption or foul your tub’s water heater. Fortunately, you can control metals by using an additive when you change your water.

Follow the manufacturer’s instructions when using metal-removing products. You will probably need to add this product each time you add make-up water or refill your hot tub. Be sure to clean your filter after using the product or you may have to use a metal removing product on a weekly basis.

cleaning your hot tub

Your Hot Tub Filter

It is very important to keep your hot tub filter clean and it’s something you should do at least monthly. We recommend that you clean your filter with a good specialized hot tub filter cleaner a few times before it gets so bad you need to replace it. By the way, Poseidon sells every type of hot tub/spa filter if you do need a replacement.

Preventing Hot Tub Scum Ring

The first line of defense is regular water replacement and proper sanitation. A scum prevention product such as Leisure Time's ENZYME can also be used to help prevent the build-up of oils and greases on the water surface that combine to form the dreaded scum ring. If it’s too late and you’re already a scum victim, use a multi-purpose spa surface cleaner and a cleaning pad that will not scratch the acrylic surface of your tub. And for that situation you can get Leisure Time's CLEANSE water line cleaner.

Cleaning Your Hot Tub Cover

Use a cover care product at least once per month. Find one that has UV protection and is good for cleaning and conditioning your cover. Again Leisure Time to the rescue: we supply Cover Care & Conditioner.