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What is an HMA System?

A heavy metal axe (or HMA for short) filter system removes dirt, sediment, chlorine, and heavy metals from the water supply.

The most typical application is within aquariums and ponds, where water must be treated in certain ways to make it safe for aquatic life. The system can also be used for regular drinking or household water supply too.

How do they Work?

Typically, these systems are made up of two to three filter cartridges. The first is a dirt and sediment filter, which will filter out physical particulates that can contaminate the water supply. The second is usually a carbon filter and the third is either a carbon filter with media like KDF for heavy metal removal or another type of heavy metal removal media. These can be carbon blocks or GAC filters depending on the system, however, they all serve the same purpose of filtering out chemical contaminants, namely chlorine and metals in the case of HMA systems.

They work very much in the same way as a RO system, and in fact, the filters found in an HMA system are the same as the ones at the beginning stages of the RO process. An RO filter will go through a dirt and sediment filter and then onto a carbon filter but will then also go through an RO membrane and then a de-ionization resin to produce a cleaner end product.

What are the Benefits of an HMA System?

So, if an RO system produces cleaner, safer water, then surely that’s the one you should go for? Well, not necessarily. HMA systems can be of particular use to fish keepers thanks to a few key benefits.

Less Waste

RO systems produce cleaner water, we aren’t going to dispute that here. However, the cost of doing business with an RO system is a whole lot of wastewater. To flush away the filtered contaminants, RO systems use their own water supply to do so, meaning that for every litre of purified water, you get from your taps, it will have used roughly four litres to produce that (on average – RO systems wastewater ratios can vary depending on membrane size and system efficiency). That’s a lot of water, and money, literally running down the drain.

Let’s compare that with an HMA system. Every drop of water that you feed into an HMA system will be purified and dechlorinated and will make it out on the other side, with no waste whatsoever. That’s a much more efficient purification process than an RO system, which means more cash is left in your wallet. Especially when you consider this through the lens of maintaining multiple aquariums or a garden pond where you’ll be using plenty of water during water changes, the potential savings for an HMA system become very enticing.

Retains Essential Minerals

Ok, so we know RO systems are good (the best!) at removing total dissolved solids, contaminants, and minerals from water. However, RO is actually TOO good for some aquariums, as it removes those essential minerals which are needed for the water to remain stable. If you were to use an RO system, you would have to add those minerals back in after the filtration process. With an HMA system, you are only removing the chlorine, sediment, heavy metals, etc… which is what you actually want to remove. No remineralisation is needed!

Cheaper Than Chemical Treatment (In the Long Term)

One of the easiest and most common ways that household water is treated for fishkeeping is through the use of chemical dechlorination treatments. Industry-leading products such as SeaChem Prime chemically neutralise chlorine and chloramine as well as detoxify ammonia and nitrates in a way that maintains safe conditions for your fish.

However, this process is a never-ending cycle of manual treatment, which means manual measuring, which means you’ll likely run out before long, then you’re on the hook for another bottle, and then another, and so on.

This is one of those classic situations where the initial cost for an HMA system might look daunting, but it’s really an investment, that if you’re in it for the long term will always prove cheaper than constantly rebuying chemical solutions. Also, you are essentially adding a chemical into the water to eliminate another chemical, which seems quite counter-productive and counter-intuitive. On top of that, you get the bonus sediment and dirt filtration that chemicals cannot accomplish, which I’m sure your fish would thank you for if they could.

Hands-Free Work

Part of the regular maintenance of a healthy fish tank or pond is regular water changes. There is plenty of different information regarding this process, some will tell you to change 5%, others 15%. Some will tell you to change your water every week, others will say you can leave it up to four weeks between changes. Regardless of what timings and measurements work for your situation, the process requires you to keep track, maintain a schedule and manually change the water out yourself. On top of this, you have to make sure the new water is treated and ready to go before you introduce it to the tank or pond, whether by a chemical treatment (see above) or simply by letting the chlorine dissipate, which will require you to leave the water to sit for a day prior. Unfortunately, if chloramine was present in the water then this would not dissipate or “gas” off.

An HMA system can take care of this process all by itself, without the need for any manual maintenance. By equipping the HMA filter with some simple piping fitted with drip tips, you can have the system constantly drip-feeding your tanks with purified water. This is essentially performing a continuous water change, meaning that you don’t have to think about schedules or percentages, all you need to do is to set the rate at which the filtered water will drip into the tank.

Should I Buy an HMA System?

There are plenty of reasons to invest in an HMA system, but that final decision will rest on whether your situation will really be getting the most bang for your buck out of your investment.

The other thing to consider is the scale of your pond or aquarium set-up. We’ve talked about having reduced water waste and being able to take a more hands-off approach to water changes, and these can be big, deciding factors if you are dealing with a large pond or multiple tanks.

Look at the benefits you could stand to gain and see how they’d stack up in your situation. If you’re a dedicated fish keeper with a long-standing interest and a lot of fish to care for, then you’ll have the most to gain from purchasing an HMA system. If you like to be efficient and cost-effective with your options, then an HMA would be a good fit within your setup.

What to Look for When Buying a HMA System.

Filter Capacity

Different systems will be rated able to efficiently purify different amounts of water before they need replacing. This amount is what’s known as the filter’s “capacity” and is typically measured in gallons.

Generally speaking, a larger filter capacity is always desirable. Whether for large home aquarium setups where you’re using plenty of water, or for a small, solo tank, higher capacity filters will be able to purify more water for you before you need to think about spending money on replacement cartridges.

Look for high-capacity filters where possible, particularly if you’re looking to purify a large amount of water.

Is it a Two or Three Stage System/

HMA systems tend to come in two sizes: two stage and three stage. The two stage systems begin with a sediment filter that removes physical particulate such as sand, dirt, and other sediment. The second filter is then a carbon and KDF filter, which is responsible for removing chemicals such as chlorine and heavy metals. The KDF filter is sometimes replaced by a carbon block or loose media which is also capable of removing heavy metals.

The three stage systems add another carbon filter into the process, which will further reduce chlorine within the water. Whilst the two different sizes of system perform very similar processes, the three stage systems usually have a longer lifespan thanks to the addition of that extra carbon filter.

Cost of Maintenance

As well as considering the cost of the system itself, it’s always important to keep in mind the sort of ongoing costs you can expect to pay for regular maintenance. Generally, this maintenance comes in the form of regular cartridge changes, so be sure to do your research on how much a compatible replacement cartridge costs for the system you’re looking at purchasing. Do remember though that not all cartridges are made equal and differ in pricing depending on performance.

Where Can I Buy an HMA System?

If you’re reading this and thinking “wow, those HMA filter systems sound super amazing, where can I get one?”, then we have just the thing for you. At Finerfilters we offer a range of HMA systems that are each tailored for different applications, be it drinking water or aquatic care. These kits are easy to install and come with all the tools you need to do so and are a great way to easily upgrade your home water filter solution.


Shop HMA Systems for Fishkeepers