Shark Cage for Maelstrom Original



Shark Cage for Maelstrom Original

The Shark Cage for Maelstrom Original delivers massive amounts of water to your tank. The single skin Shark Cage uses super-fine filtration to block leaves and debris, keeping your water clean.

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SKU: RHML03 Categories: ,

Rain Harvesting Shark Cage for Maelstrom Original


The Shark Cage Filter is the step up from a standard Maelstrom – it’s incredibly easy to clean and handles higher flow rates of water – which means more water in your tank. Installation is as simple as lifting out the plastic filter and dropping in the new Shark Cage.

Maximum Efficiency

Even more efficient water capture than a standard Maelstrom. The single skin, stainless steel cage, allows debris to be pushed to the side so you catch as much water as possible.

Ultra Fine Filtration

Removes particles down to 180 microns – That’s five times smaller than standard tank screen!

Minimal Maintenance

The unique design of the Shark Cage means that debris is pushed by the incoming water, and when debris loads start to build, it will start to self-eject leaves from the filter.

Stainless Steel Cage

The Shark Cage is built from stainless steel. It’s tough and it’ll last.

Easy Upgrade

Just lift out your existing plastic Maelstrom Filter and drop in the Shark Cage Filter.



How it Works

Water enters the system through an inlet, before filtering through the super fine Shark Cage Filter.

The unique design of the filter knocks the energy out of the water, allowing it to then fall into your tank.

Leaves and debris are pushed to the side, and in many instances will wash out the dirty water outlet on the top, providing a level of self cleaning.

Huge water catchment with incredibly fine filtration.



• A single point, tank-top filter with a ground breaking stainless steel shark cage design
• The 180 micron filter screens particles 5 times smaller than is achieved with a standard tank screen
• Reduces the hassle of cleaning leaf and debris build-up through Self-flushing
• Blocks out light that supports algae growth.
• Is a versatile product, able to be installed in a variety of pre-tank locations
• Reduces frequency and cost of tank cleaning by lowering common sediment build up through cleaner tank water
• Mounting plate fits 300mm, 400mm and 500mm tank openings, or can be used for mounting in-tank, on wall or in a pit


High water catchment

The Maelstrom with Shark Cage Filter delivers large volumes of clean rainwater to your tank, giving you unrivalled performance and rainwater catchment. By preventing leaves, debris and other unwanted materials from entering your rainwater system, water can move through your downpipes faster, more freely and without blockages. With less inhibitors in your system, you will capture more rainwater.

Super-fine rainwater filtration

The Maelstrom with Shark Cage Filter will filter rainwater to 180 micron to deliver high-quality, clean water directly to your storage tank, making it ready for use. The unrivalled, super-fine filtration of the Maelstrom with Shark Cage Filter provides you with the comfort and peace of mind in knowing that your rainwater catchments will be receiving superb filtration to prevent unwanted particles and matter from entering your system.

Easy to maintain

The Maelstrom with Shark Cage Filter can be very quickly and easily cleaned, reducing overall maintenance and helping to keep your system intact. The single skin, stainless steel mesh filter can be easily removed for fast cleaning, keeping leaves and debris out of your system entirely. Easily reattached when cleaning is complete, your system will stay working as required and deliver you plenty of clean rainwater.

Installation Guide

Tools you may need

  • Screwdriver
  • Adjustable spanner

Shark Cage Filter Upgrade For Maelstrom

1. Remove the lid on your Maelstrom unit by undoing the 4 clips around the outside.
2. Remove your existing Maelstrom blue filter by pulling upwards on the black handle.
3. If there is any debris inside your Maelstrom housing, now is a good opportunity to clean it.
4. Fit your new Maelstrom Shark Cage filter by inserting it into your housing. The ideal way to do
this is by angle the 2 circular rubber inlets into position first, then pressing down the back of the
Shark Cage until it is resting on the ribs of the housing.
5. Note the fitment of your Maelstrom Shark Cage. There is an adjustable bracket at the rear of the
filter that allows you to tune the fitment. The filter should fit snugly in position. If required, use an
adjustable spanner or screwdriver to adjust the length of the bracket.
6. Replace the lid on your Maelstrom, making sure that all 4 clips are secured.


For best performance, check and maintain your Maelstrom on a regular basis. The required
frequency of maintenance will depend on the environment in which your Maelstrom is installed.
High debris areas will require more regular maintenance than low debris areas.
To determine how frequently maintenance will be required in your location, we recommend
inspecting the Shark Cage filter after the first rainfall event and planning your maintenance
schedule based on this initial inspection.
To clean your Maelstrom, unlatch and remove the lid.
Grasp the handle on top of the filter and lift it upward to remove. Scoop out any large pieces
of debris by hand, then use a hose to wash out the Shark Cage filter. If required, you can use a
brush to remove any debris. Lift the mosquito proof screen out and brush or hose off any debris
on either side of the screen.
Replace the mosquito proof screen, ensuring it sits securely in place. Reinstall the Shark Cage
filter to its position within the filter housing, then replace the lid and secure it with the latches.


• AS/NZS 3500.3:2003 Plumbing and Drainage – Stormwater Drainage
• enHealth Council
– Guidance on the Use of Rainwater Tanks
– Preventing Mosquitoes Breeding
• HB230:2008 Rainwater Tank Design and Installation Handbook
• Queensland Health Regulations 1996 (Part 8 – Mosquito Prevention)



How often should I clean my Maelstrom’s filter screens?

Every environment is different, so the necessary frequency for cleaning your filter screens will vary. We recommend checking your Maelstrom filter regularly after installation to determine the rate at which debris accumulates. You can then use this information to make an informed decision about cleaning frequency. Depending upon your needs and situation, you may determine that cleaning is required monthly, quarterly, after each heavy downpour, or at a different frequency.

Do I need to modify the tank inlet when installing my Maelstrom?

No. Your Maelstrom is supplied with an adjustable flange that is designed to accommodate existing 300mm, 400mm and 500mm inlets. Simply remove the existing tank screen and trim the flange to suit the size of your inlet hole.

What head height is required when installing my Maelstrom on the inlet side of a wet or “charged” system?

Your Maelstrom filter should be installed no less than 500mm above the inlet of the tank.
When the Maelstrom overflow is connected to an outlet, for example, a stormwater discharge, the wet system head height can be reduced to accommodate low head systems. Collection efficiency is traded-off against low head height filtration.

What is the Maelstrom’s maximum flow rate?

On a wet rain harvesting system, your Maelstrom can handle water flowing at 10 litres (2.64 gallons) per second with a water catchment efficiency of 96%. It can handle water flowing at 5 litres (1.32 gallons) per second with a 99% water catchment efficiency for wet systems. Above 10 litres (2.64 gallons) per second, your Maelstrom will direct excess water to the outlet port (overflow).

Used in a wet rain harvesting system, your Maelstrom will yield 99% filtered water catchment at 5L/sec and 96% filtered water catchment at 10L/sec.

Are replacement filter bags available?

Yes. Replacement filter bags are available for your Maelstrom filter. The Maelstrom bag is designed to be reusable and can be washed and reinstalled. In the unlikely event that your bag is damaged or lost, replacements are available from Blue Mountain Co.

Can I connect multiple pipes or “lines” to my Maelstrom?

Multiple pipes can be consolidated before they reach your Maelstrom filter. However, it is important to assess the impact of consolidating these pipes to ensure that your total system flow is not restricted.

Can I install 90mm pipe to my Maelstrom?

Yes. You can use a tapered reducer or LIT (level invert taper) to connect 90mm pipe to your Maelstrom’s DN100mm inlet and outlet ports.

Can I install inlet pipes to both side ports so I have two inlets rather than one inlet and one outlet?

No. We do not recommend installing inlet pipes to both side ports. It is important that one side port is dedicated to overflow to allow your Maelstrom to perform its self-cleaning function and prevent clogging.

Can I install a first flush before my Maelstrom?

Yes. First flush diverters can be installed before or after your Maelstrom filter. If you choose to install a first flush diverter upstream of your Maelstrom, make sure you install a screened rain head before the first flush diverter so it cannot be clogged with leaves and larger debris.

Can the Maelstrom be installed in the charged area of a charged system? Ie. Can the Maelstrom be positioned below the inlet of the rainwater tank.

No. Your Maelstrom filter is not designed to carry a head of water, as the filter uses a self-cleaning gravity feed action to discard debris from the flow of water.

However, you can install your Maelstrom filter on top of your tank in place of your tank screen (or beside your tank) as the final filtering point for your wet system.

What do I do if there is a significant amount of water coming out of the debris overflow of the Maelstrom?

Check the following:

  • Check the blue internal filter if there is a large amount of debris
  • Check the fine bag filter if there is a lot of fine debris
  • Clean either of the above filters if required

If the rainfall event is extreme, it is possible for some unfiltered water to overflow from the debris overflow port. Refer to expected flow rates section.

How do I collect the maximum amount of water from my Maelstrom?

The best way to maximise the amount of captured water from the Maelstrom is to:

  • Ensure the filters are maintained periodically
  • An alternative setup for the debris overflow to maximise clean water catchment is to add a small upwards bend, which will help to slow the flow of water at the debris overflow – forcing the water through the Maelstrom’s filters. In this scenario, it is recommended to maintain your filters more regularly since the debris is forced to flow over the bend.
Weight 2 kg
Dimensions 31 × 30 × 18 cm


Rain Harvesting

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