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How To Clean Hot Tub Filters

How to clean hot tub filters
If you are looking for information about how to clean hot tub filters then you will find the information contained on this page to be specifically useful. Most hot tub owners do not appreciate just how much heavy lifting that the tiny little paper filters in your spa need to do. As someone who has spent years working behind a hot tub water lab desk I can easily say that dirty spa filters account for the majority of ongoing water chemistry and water clarity problems in residential hot tubs. If you are not cleaning your filters properly, which a surprisingly high number of people do not, or if you are not changing your filters often enough, then you could anticipate excess foam and bubbles in your water, turbidity, grey-looking and listless water, funny smells, an oily film on the water, and an inability to regulate and manage the chemical values in your water...does ANY of that sound like a good time to you? Yeah, me neither. Fortunately the solution to these problems, and to having clean hot tub filters, is actually fast, easy and cheap - it does not get a lot better than that people.


First of all let's address the important question of "how often should you change the filter in a spa?" and the simple, if not somewhat cheeky, answer is to change them every time they get dirty. I think a common period of time that spa owners might be advised to wait in between filter changes is about a month. For myself 30 days is WAY too long of a time. I have a smaller spa which I use daily, and if I went 30 days in between filter changes then my water would be a disgusting and uninviting mess. I can not imagine what it would look like if more than just myself or my wife used the spa...no kids or neighbors or anything like that and I would still not go 30 days between filter changes. If you have been advised you can go this long then I would encourage you to reconsider your maintenance schedule.


Is it important to change your hot tub filter? - The thing about changing the filter in your hot tub is that it makes a profound difference in the performance of your tub and the clarity of your water. Instead of taking a minimal approach to maintaining your filter I always encourage my clients to be liberal with how often they change and clean their filters. For example if I put clean filters in my spa yesterday, but then I had a party with a few people over using the spa, I would change them the very next day. That is less than 24 hours of running time in the water. So why would I do this? Why wait until the filter is completely saturated with sweat and oil and makeup and toe jam...change it often and keep all of that junk out of your water. At minimum I put fresh, new and clean filters in my spa every week. It is fast and easy to swap filters in almost any hot tub and being more proactive with this maintenance task is going to pay dividends in water clarity, reduced foam and reduced chemical demand.


Don't throw out your old hot tub filters
Can hot tub filters be reused? - A surprising number of hot tub owners do not actually know that the filters, by and large, are meant to be cleaned and reused dozens of times over. I have met with many spa owners who threw out their filter every time it got dirty. The confusion here comes from a small amount of spa filters which are intended to be disposable. These filters might often look more like cotton wrapped tightly in netting, as opposed to the much more common reusable (pleated) paper filters that you are not supposed to throw away after every use.


A hot tub filter of the pleated paper variety should last you at least a year in the spa. If you swap out multiple sets of filters then you can expect at least a year of service life in the water from each set.


Since hot tub filters are usually pretty cost effective when you consider that you will get a year of use or more out of each set you have, it makes sense to buy and own a few sets of filters for your spa so that you can minimize the amount of work you need to do. Simply put new filters in your spa once per week and when you have a few dirty filters then you can clean them all at once using the method shown in the video below.


Where should you buy your hot tub chemicals? - Almost universally I tell spa owners to avoid shopping at big box stores, hardware stores or grocery stores for pool and spa chemicals. You are much further ahead to buy everything you need from actual hot tub retail stores where the quality (and shelf stability) of their chemicals far exceeds the generic crap that big box stores tend to sell. One of the only exceptions to this general rule I have is in regards to hot tub filter cleaning solution. If I only cleaned my hot tub filters every 30 days or less it would not be such a problem, but because I see value in cleaning them much more often than this the hot tub filter cleaning chemicals would end up being the most expensive thing I use in my water...which it should not be. Sanitizer like bromine is expensive (for the good stuff) and should easily be the most expensive thing you are buying regularly for your spa. Perhaps enzymes as well as they are specifically useful but a tad on the expensive side as well, at least when compared to acid and baking soda.


What is the cheapest way to clean hot tub filters? - There are two different treatment options for a paper hot tub filter. One is a degreasing procedure and the other is an acid bath to remove scale that can develop on the paper an greatly inhibit flow. Unless you can see physical scale falling off of your filters then chances are you only need the much more common cleaning process of degreasing. The filter is made from paper and it absorbs many of the oils that end up floating around in a hot tub. By soaking the filter in a detergent degreaser this will break down and strip out the oils that are saturating the paper. So what kind of detergent is used for this process?


1) The detergent should be specifically made to cut through and break down grease and oils

2) The detergent should NOT be a kind of soap that foams up or causes bubbles

3) The detergent must be free of phosphates



These three qualities are what you need from any hot tub filter cleaning chemical. As it turns out there is an option that is commercially available and very inexpensive which can satisfy all of these requirements. Since I clean my filters so often and needed a more cost effective way to do so, I use automatic dishwasher detergent. This is a soap that is made specifically to NOT bubble or foam, and it also is made to cut through grease and oils to get your pots and pans sparkling clean. If it is safe enough to wash my cutlery and plates with then I suppose it is safe enough to wash hot tub filters with as well.


Finally, and perhaps most importantly, it MUST be phosphate free. Phosphates are a definite problem for pools and spas, and this is why people who live near golf courses or rural farmland runoff often struggle to maintain their sanitizer levels. All sources of phosphates should be eliminated in and around a pool or spa and phosphate remover chemicals should be used on any pool or spa that is found to have elevated phosphate levels above 500 parts per billion. Fortunately there are many generic and inexpensive brands of automatic dishwasher detergent which are phosphate free so you should not have any trouble to find some.


Using this product allows me to change my filters every week at a minimal cost for filter cleaning chemicals. I can usually mix up a five gallon bucket of filter cleaner around 10 times with one box of automatic dishwasher detergent that costs no more than a few dollars. That is between 20 to 30 cents for each five gallon batch of filter cleaner solution I make up. You can't get a lot better than that.


How to clean a spa filter - Once you have soaked the filter in degreaser you need to rinse it very thoroughly. This is a time consuming process since the pleats of the filter are inclined to trap hair and organic debris. Many hot tub owners only rinse their filters, neglecting to do the critically important degreasing soak, and rinsing your filter with cold water and a garden hose will not remove the grease and oils saturating the paper. The rinse process after soaking your filters in degreaser is important to remove the physical debris within the pleats, but also to ensure that you have rinsed all of the detergent residue from the filter before returning it to your spa. Even though the detergent is designed to not foam or cause bubbles, you definitely want to avoid adding any soaps to your hot tub...which is why it is important to rinse yourself and your swim trunks before you get in a pool or spa - it is just more important in a spa because of the much smaller volume of water that you are getting in.





It is very important to rinse your filter well after soaking in detergent which can be challenging since the pleats tend to hold debris and rinsing thoroughly with a garden hose can take forever. To make the rinsing process easier, faster and more thorough you should pick up one of these Aqua Comb tools.





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Is there such a thing as a chemical free hot tub?

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