Marineland Magnum 350

Written by Kmuda. Posted in Canister Filters



  •  Easy-to-use canister filter with patented bottom-mounted motor
  • Versatile aquarium filter converts from continuous duty to water-polishing mode
  • Large chemical filter media container for a clear and clean aquarium environment

The only filter of its kind with a patented design, self-priming, bottom-mounted motor, the Magnum Canister Filter provides the ultimate in easy setup and restart capability. Magnum is two filters in one: it converts from continuous duty to water polishing, and all Magnums now come complete with a Carbon/Media Container and Water Polishing Micron Cartridge. Water enters the canister, surrounds the media, and flows through rather than around it. No bypass ensures total filtration. All Magnum canister filters we carry have a certified flow rate of 350 gph, making them the ideal choice for aquariums up to 100 gallons. 2-year manufacturer's warranty.

Magnum Canister Filters convert easily and quickly from continuous duty filtration to quick-clean water polishing... and back again. A Magnum silently does the heavy duty work of two complete filtration systems and delivers total water-to-media contact... no bypass. No-compromise technology and highest quality materials ensure unit strength, durability and trouble-free operation.

Magnum 350 Deluxe

Includes: Carbon/Media Container, Water-Polishing Micron Cartridge, Rite-Size Foam Sleeve, Black Diamond Premium Activated Carbon, Double Quick-Disconnect Valves, Flexi-Brush, Intake Extension Tube.

Magnum 350 PRO System

The 3-in-1 Magnum 350 PRO System filtration package delivers optimum mechanical, chemical, and patented BIO-Wheel PRO 60 classic wet/dry biological filtration.

Proper filter maintenance begins with frequent visual inspections to ensure normal system operation and non-stressful conditions for fish. Additionally, every aquarist should plan to devote an average of 15 minutes per week to the performance of basic maintenance and needed adjustments. These requirements include monthly, 25% water changes and gravel cleaning, as well as regular (once a month, minimum) filter media replacement. Unusual occurrences – such as lack of water flow, excessive mechanical or water noise, cloudy and/or bad smelling water – require immediate attention.

*IMPORTANT: Because all water circulation in a canister system must first pass through the filter media, extra care must be taken to ensure that clogged media does not reduce the efficiency of the filter. Carbon needs changing each month – sooner if it is no longer effectively removing discoloration or odor from aquarium water.

NEVER use soap, abrasives or any other cleaning agent on or around filter or aquarium. Clean with water unless otherwise instructed. Never attempt to open the Motor Housing or submerged Motor Assembly.

  1. Turn Motor Switch to "OFF." Close valves and disconnect. Remove canister.
  2. Change Filter Media:
    CARBON/MEDIA CONTAINERRemove media and rinse container thoroughly. Refill container with Magnum Activated Carbon and rinse carbon thoroughly. Rinse or replace Rite-Size Sleeve.

    MICRON CARTRIDGE Remove and clean cartridge – never brush or machine wash. Rinse off all visible dirt. Mix a solution of one part chlorine bleach to three parts water in a separate container. Immerse cartridge completely in solution and soak overnight. Rinse thoroughly until chlorine smell disappears.

  3. Clean canister thoroughly, especially sump area.
  4. Clean Impeller Assembly and inspect for wear and smooth rotation. If excess wear is noted, replace worn parts immediately.
  5. Gently clean flat rubber gaskets with warm water only.
  6. Wash O-ring seating area on canister and cover. Wet O-ring before installing.
  7. Reassemble system and return to operation.

Marineland Magnum 350 Review:

By Kmuda


Next to the Eheim Classic filters, these are the "grand daddy" of Aquarium canister filters as they've been in manufacture, virtually unchanged, for decades. Like the Eheim classics, their beauty is in the simplicity of the design. I personally have a Magnum 350 that has been in constant use for approaching 20 years (with no parts replacement). I have another Magnum 350, purchased a few years back, that is identical to the one purchased 20 years ago.

Unlike the Eheim Classics, these filters are rarely recommended due to their size (lack of media volume), although with Simple Modifications and use of the biowheels (in the Pro models) they make excellent, reliable to an extreme, filters.

For mechanical filters, if using the Micron cartridge, they can't be beat. So if nothing else, they make great water polishing filters.

Personally, I use mine as secondary filters, modifed for biofiltration, although historically I have used them as standalone (solo) filtration on tanks up to 55 gallons.


  • Made in the USA
  • One of the most dependable filters on the market. There are examples of this filter being in constant use for over 20 years
  • Very easy to work with, no mess maintenance, easy to move around
  • When using the Pro model, Biowheels provide great, non-clogging biofiltration
  • When using the Micron Cartridge, mechanical filtration can't be beat
  • Compact size can fit almost anywhere
  • Filter has an On-Off switch, a concept that more filters should adopt
  • At 350gph, flow rate is respectable
  • Design of the filter ensures no water bypasses the media cartridge
  • Marineland Customer Support
  • Is a low cost, easy to use alternative for 55 gallon or smaller tanks. A great secondary filter for larger tanks.
  • Bottom mounted impeller is a design concept other manufactures should investigate
  • This filter has been around forever, spare parts are readily available


  • Filter is designed primarily for mechanical or chemical filtration, with the biowheels providing biofiltration. However, with this design, only a percentage of the water passes over the biowheel, which limits its effectiveness as a biofilter. You have to think a bit outside the box if wanting to use this as a biofilter. The recommended (and simple) modifications linked previously (see above).
  • There is only a single container for media, with this container designed primarily for activated carbon. I fill this container with Eheim Ehfilav or Eheim Substrate Pro for increased biofiltration. However, the amount of media that can be employed is limited when compared to other filters.
  • Installation, especially with the Pro version, is a bit more complicated that with other canister filters.
  • The filter ships with "rubber band" like clamps designed to provide a tighter seal on the hose splice connections necessary in the installation of the filter. It is the intent of these "rubber band like" clamps to prevent leaks. They don't. So use of standard hose clamps (which must be purchased seperately) are recommended.
  • The quick disconnects, while functional, leave something to be desired.

Other information:

  • If using this as a primary filter, or if wanting to increase biofiltration, refer to the links located in several places above for the recommended modifications.

Recommended Maintenance Proceedure:

Note: The below instructions assume you are using the Magnum 350 Simple Modifications.

  1. Fill a bucket with tank water
  2. Turn off the filter
  3. Remove the biowheels from their housing and shake them out into the bucket of water, then place them back into their housing
  4. Engage shutoffs on both the outflow and inflow tubes
  5. Disconnect the quick disconnects, lift the filter off the motorhead, and carry the canister to a sink.
  6. Open the disconnect vaves to release pressure inside the filter (otherwise you'll stuggle to get the lid off).
  7. Unhook and remove the filter lid.
  8. Remove the media container, seperating the blue bonded padding from the container (placing it into the sink) and dump the media into the bucket of tank water.
  9. Swirl the media around, rubbing it against each other, to dislodge gunk that has built up.
  10. Rinse the blue bonded padding in the sink (I use the dish sprayer attachment), being sure to turn it inside out to get both sides.
  11. Remove the plastic tube that mounts on top of the impeller, and the impeller, from the filter housing. Rinse both, using a toothbrush to clean the slime from the surface. Also rinse the rubber gaskets.
  12. Using a q-tip, filter brush, or toothbrush, clean the impeller housing.
  13. Place the impeller back into the housing, then the plastic tubing (note, look at the hole sizes in the base of the plastic tubing, lining up the different sized holes with the associated "pegs" in the bottom of the filter casing.
  14. Remove the biomedia from the bucket, placing it back into the media container
  15. Slide the blue bonded padding back around the media container, placing the media container back into the filter
  16. Fill the filter with dechlorinate water then place the lid back onto the filter, securing it with the latches
  17. With both disconnect valves open, pour dechlorinated water through one of the filter tubes until water runs out of the other tube
  18. Close both disconnect valves
  19. Carry the fitler back to the tank, place it back onto the motor housing, reconnect the tubeing, opening both shutoff valves
  20. Turn the filter back on