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Weighing the pros and cons of a cartridge and a sand/fibre ball filter for your Gardenvity wood-fired hot tub

compare sand filter and filter cartridge

Gardenvity’s two distinct product lines, Premium and Essential, have different filtration systems – cartridge filter and sand filter used with fibre balls. Both methods work effectively in a small water vessel, such as a hot tub. Still, there are differences in operation and maintenance, and the decision comes down to personal preference. 

Find the article on a sand filter used with filter balls here, while this article will compare the two types of filtration systems, hoping to help you make an informed choice. 

  1. The main facts about a sand/fibre ball filter
  2. Why a cartridge filter is a good choice
  3. A side-by-side comparison of the two filtration systems
  4. Bottom line facts

1. Sand/fibre ball filter – effective and environmentally friendly

Sand filters, which are the oldest water filtration system used in swimming pools, previously used natural filtering media – hence their name. The technology has been significantly improved by replacing sand with more effective modern filtering media, such as fibre balls to trap smaller particles (down to 5-3 microns compared to 35-20 microns with sand). The modern filtering media also plays an important role in reducing energy consumption, keeping the filter pumps under lower pressure. What is more, the fibre balls can be recycled to make it an environmentally friendly solution.

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2. Cartridge filter – lower initial investment and simple operation 

Cartridge filter cassettes are super lightweight and can be replaced with one hand within minutes. Modern filter cartridges capture debris and impurities as small as 5 microns (a human hair, for example, is 40-60 microns in diameter). The cartridges used in Gardenvity wood-fired hot tubs should be replaced every 3 weeks, as per the manufacturer’s recommendations. Still, this period can be easily extended to a whole month or more with a little bit of care. This, of course, depends largely on the usage and water quality.

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3. Side-by-side comparison of filtration systems in Gardenvity wood-fired hot tubs

The table below shows a summary of the pros and cons of the two different filters used in Gardenvity hot tubs as well as how much it is going to cost to operate and maintain them. Please bear in mind that the prices of the filtration systems shown in the ‘Money’ part below include the filter units, fittings as well as all the engineering works that need to be carried out.

Sand filter with fibre balls

Cartridge filter


  • Captures impurities down to 5 microns in size
  • Fibre balls last for 2 years
  • Easy maintenance requires washing the filter balls only occasionally (we recommend inspecting them every 3 months and washing if needed) 
  • Replacing the filter balls is effortless
  • Forms larger filtration area with low stress on the filter pump saving on energy consumption
  • Friendly to the environment – the fibre balls are recyclable and wear very slowly
  • Captures impurities down to 5 microns in size
  • Filter cartridge serves 3 weeks, which can be extended to a month or more when washed at least once a week
  • Easy maintenance – replacing filter cartridge takes only minutes
  • Lower initial investment 


  • Some filter balls have to be taken out from the filter tank, soaked and washed manually before they can be re-used, which requires some effort
  • Higher initial investment (filter unit price + filter media)
  • Regular cartridge replacement increases the cost of maintenance
  • Non-recyclable filter cartridges


Maintenance costs

Year 1 – none*

Year 2 – none*

Year 3 – fibre balls, £17 

Total in 3 years: £17

Power costs 

Working non-stop at 250W power, based on current average electricity prices in the UK, the sand/fibre ball filter would consume £30 per month.***

Maintenance costs

Every year – 1-2 filter cartridges (£4 when bought larger quantities) per active month, up to £96 per year.**

Total in 3 years: up to £288

Power costs 

If powered all the time, the 99W filter pump would consume £12 per month.***

* You will only need to wash the fibre balls either by hand or in a washing machine (put them in a washing net when doing so!) every few months. 

** This number will vary widely depending on the usage anywhere from £48 a year, if used moderately, changing the cartridge once a month, to £8 per single month when used intensively, reaching £96 when used that way all year-round. 

** The given estimate is the highest possible figure. Non-stop operation is not necessary. A water filter needs to be run 4-5 hours daily when the hot tub is filled with water.

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4. Bottom line facts 

Any type of water filtration system is going to occasionally require a few minutes of your time, be it opening and cleaning the strainer, washing the fibre balls in the sand/fibre ball filter, or inspecting and flushing the filter cartridge. 

The quality of the water coming through a cartridge filter or a sand filter used with modern filtration technology, in both of which particles as small as 5 microns are captured, is comparable. 

The maintenance work needed for the cartridge filter is much simpler, but the cartridges have to be bought and replaced more often than the fibre balls. Also, the filter cartridges are non-recyclable, rendering the method less environmentally friendly. 

The initial price difference between a sand/fibre ball filter and a cartridge filter balances out within a few years (the more intensive usage, the sooner it will become more economically effective to use a sand/fibre ball filter). The sand/fibre ball filter option is likely to become the cheaper option in the long run.  

Be advised that without any water filter, you will need to replace the water in your hot tub after 1-2 uses in 1-2 days. Having read all the above, we hope it becomes easier to see which type of water filter checks more boxes of your preferences.

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