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Marineland Magnum 350 Filter Review



For years I've used a Diatom filter for water polishing.

For those not familiar with the diatom it uses diatomaceous earth as a filter media - diatomaceous earth or DE are tiny fossilized organisms called diatoms which are crushed to an extremely fine powder.

DE has the ability to filter out pathogens as small as one micron - it's the only material of it's kind that can filter out parasites like ich.

That said, they are incredibly cumbersome to use.

Set up alone even for the experienced is difficult and time consuming. You need to be able to open the motor casing, replace bearings, oil certain parts, replace gaskets, apply silicone, clean out the motor and more.

It's a fine product that does exactly what it promises to do but again, very difficult to set up, break down and maintain.

A long time fan of many Marineland products - the Magnum 350 caught my interest because it can double as a water polishing system. Instead of the DE it uses long hollow cartridges of a tightly woven pleated material similar to Hepa filters for cleaning the air.

Having a few questions I placed a call to Marineland and found out the polishing cartridge will remove particles as small as 10 microns (about half the size of the dot over a lower case i) I would think most people this is more than adequate.

When I asked about using DE the Marineland tech told me that using it was fine and can't obstruct the impeller, void your warrantee or cause any problems.

So you can easily get the filtration down to one micron - free of the hassles involved with a Diatom filter.

The Magnum 350 is the only filter of it's kind that can convert from a mechanical filtration canister - to a water polishing system.

Set up is a breeze as is break down - and the results are fast and spectacular. I tried it out on a 55 and within two hours the water was unbelievably clear, pristine and gorgeous. As I write this review it's currently polishing another tank.

Included in the box is more than enough hose then you'll ever need, the motor, canister, gaskets, O-rings, a pre filter sleeve, in take strainer and out flow with diffuser.

Also included are two handy quick disconnect vales - one for in take and one for out take.

These let you un hook one or both hoses without water gushing out everyplace and either move the filter to another tank for polishing or simply empty it and put it away.

They even toss in a couple of quality Flexi Brushes for cleaning out hosing and filter parts.

As a primary filter for an aquarium I would never recommend it - It's limited to mechanical filtration only. The chamber they give you for activated charcoal is far too small to hold enough biological media and you would never colonize enough nitrifying bacteria. This bacteria is essential to both neutralizing ammonia and maintaining healthy water.

Although should a filter fail on you, this would make an excellent temporary filter or perform equally well as a supplementary filtration - if you tolerate the noise level.

It comes with a jar of activated charcoal - which I never use. With the rare exception of removing medication from my tanks. Which is another plus for the Magnum 305.

The filter is fairly well made - definitely not the build quality you would find with eheim.

Some of the smaller parts are flimsy at best, but this is knit picking.

Quick Specs

* Certified Flow Rate of 350 GPH

* No water bypass

* Good for tanks up to 100 gallons

* Only filter that can convert easily from continuous filtration to water polishing

* 2 year manufacturer's warranty

* Polishing cartridges can be cleaned and re-charged with bleach solution

At the list price around $329.99 I wouldn't give it a second glance. But if you can find a good deal on it, I would say grab one. I bought mine on Amazon for $94 an absolute steal.

The polishing cartridges sell for $17.99 just about everyplace you look. However you can find them on eBay or Amazon for $8 - $9 and I've ordered a bunch of them.

As far as the Magnum 350 it's short comings are insignificant compared to how much this filter can do for you - as long as you use it for the right application.

Marineland stands behind their products. Anyone how used their Stealth heaters - which I really loved was made aware of a potential short in the wiring. I called gave the name and wattage of the heaters and shipped out replacements of a higher end heater immediately.

When I was doing the initial set up, the impeller was problematic, called Marineland did some trouble shooting and the person I spoke with took my shipping info and told me they were shipping out a new impeller assembly - good tech support is worth it's weight in gold.

My read on the Magnum 350 is it's a great filter to have, and nothing else will keep your water at this level of clarity. Even algae blooms vanish in a few hours, same with hazy new tank syndrome water - if you're using the DE.

If you think you can use it for what it does best - and find it a very...very good deal. I would highly recommend it.

You get all the benefits of the Diatom filter by Vortex - without the brain boiling headaches.

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  • Admin

Great review :thumb:

I had one and the only thing I didnt like is trying to put it back together and start it. But yes if you can get it to work its great. :thumb: Me personally if I can afford another canister its going to have to be the Eheim... Sorry :(

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  • Regular Member

Great review :thumb:

I had one and the only thing I didnt like is trying to put it back together and start it. But yes if you can get it to work its great. :thumb: Me personally if I can afford another canister its going to have to be the Eheim... Sorry :(

Why Thank ya - Koko, you should know by now the only filters I've used for the past 35 years are eheims!

All I can tell you is that if you thought the Magnum was a pain..omg..the Diatom? especially the largest one that they use in LFS which is the only model worth getting. makes the set up of a Magnum look like the tiny filter I use for my Betta.

Screw drivers, wrenches, back flushing, turning the whole thing upside down to prime it. - The manual is like a phone book, the diagrams like blue prints to a nuclear plant...ugh.

They havent changed one thing about that filter since 1972 even the packaging is the same.

Let me know when you get your eheim I'll pop open some champagne - and BTW the classic and the pro series are at rock bottom prices on Amazon. Happy shopping.

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