# Magnum 350 as a diatom filter?



## epicfish (Sep 11, 2006)

I found a used Magnum 350 filter. 3 months old, no micron cartridges, ~$29 shipped.

Is that a good deal for a filter that accepts diatomaceous earth powder? I have some GW and hope that this filter will clear it up for me.

Someone else was also selling a used Magnum 250 for $20 shipped, but I recon the Magnum 350 would be worth the extra $9 or $10?

Thanks!


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## glass-gardens.com (Apr 14, 2004)

epicfish said:


> I found a used Magnum 350 filter. 3 months old, no micron cartridges, ~$29 shipped.
> 
> Is that a good deal for a filter that accepts diatomaceous earth powder? I have some GW and hope that this filter will clear it up for me.
> 
> ...


I use a 350 with a micron cartridge on my 75, love the thing. Don't use DE powder with it though, don't see the need for it, the cartridge starts loading within 24 hours, and needs replaced with a clean one once a week to maintain decent flow. I would think DE would just about render it worthless in a matter of hours. Don't know if it will clean green water, but then filtering out algae doesn't solve algae, you need to figure out what's out of whack that's causing it.

All in all I love the thing though.


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## steve5520 (Jul 3, 2006)

I had a slightly different experience. I used a Magnum HOT 250 which uses the identical micron filter cartridge.

When I had a bad case of green water, I ran the HOT and a UV sterilizer at the same time. Cleaned it up fairly quickly.

Anyway, my experience was that the microm filter ALONE did not clean the water very quickly. Although Marineland now claims to use their filters with just the micron filter and no DE and it will work just as well. It did not.
After the first cycle, I added DE. Cleaning process speeded up considerably.

For tips on how to charge the filter with DE check here:
http://www.plantedtank.net/forums/equipment/33655-need-something-clean-up-my-water-2.html

One way or the other (with or without DE) you are going to have to watch the filter and clean the cartridge on short cycles. With DE, I could run mine between a day and a half or two days. With just the cartridge, a little longer, but not ALL THAT MUCH.

Buy two micron filters, that way when one is running, the dirty one can be soaking in bleach solution.


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## boink (Nov 27, 2006)

250 on my 75 cleaned up the cloudiness =p that is running with DE, which helps alot. BTW when do u want ur DE epic?


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## Jimmyblues (Dec 16, 2010)

I've been considering purchasing a Marineland 350 to use as a diatom filter for a small Panda Cory tank that I own which has atypical dimensions. Specifically, it's a Glasscages.com 1/2 15; meaning that the tank has the same footprint as a 15 gallon aquarium, however, is half the height.

This means that I can't use my Magnum HOT 250 filter on it, because the filter is too tall, and sucks in air when I turn it on in this tank. I use the HOT 250 to both micron filter as well as *diatom filter my other aquariums. However, as stated, the 1/2 15 is too short to use the HOT 250 on. 

*For those with Marineland HOT 250s, you can use the micron cartridge that is included with the HOT 250 to diatom your aquarium. You simply add diatom powder to your HOT 250 the way that you would with a Vortex D-1, XL, or Freedom Filter.

You can also use the micron cartridge many times before you need to replace it. Just soak
the filter in a mixture of 1 part bleach to 10 parts water overnight. Overall, these filters are pretty durable as long as they are maintained, so there's no need to toss them after you've only used them a few times.


For green water you must use diatomaceous earth, since the algae spores will simply pass through the HOT 250's micron filter when it's used without the DE. If you own a planted aquarium with injected CO2, fertilizers and high tech lighting such as T-5, it would pay to purchase a uv sterilizer to keep your water column free of algae spores.

Otherwise, you are going find yourself in a constant battle with algae as it feeds on all of the nutrients in your aquarium, which results in green water as the algae multiplies 
exponentially, having fed on all of the extra nutrients in your tank's water column.

The flow on the HOT 250 is noticeably reduced with the diatom powder. However, it's still more than enough to diatom an aquarium up to about 20 gallons in size within a half hour or so. For larger tanks, it may take you the better part of a day or two (and after a few filter cleanings) before your tank is fully diatomed. However, the HOT 250 will get the job done.

Or course, for a fast diatom cleaning, nothing works better than a Vortex diatom filter. 

In regard to some comments I have read on other fishkeeping forums - specifically, that the newer Vortex diatom filters are not as good as the originals were - perhaps these people got stuck with a filter which was assembled poorly.

I say this because I recently purchased a new Vortex XL which appears to be every bit as well constructed as my 30 + year old Vortex D-1 (which is presently in need of a service). So perhaps, there's a quality control issue here, and not an actual downgrading in the parts used by Vortex.

As for dedicated diatom filters, in my opinion Innerspace Products' Vortex diatom filters are still the best available. I have also heard that the System I diatom filter was excellent, before the company stopped producing it. I see them from time to time on E-bay and there's quite a disparity in their pricing. There's one presently for sale on Ebay for about
$25 which is sold as working, and appears to be in excellent condition. However, I have also seen these filters sell on Ebay for well over $100. So, caveat emptor.

I would use the Vortex XL on my Panda Cory tank, however, there is no way to control the flow, so it would be far too powerful to run in this tank for any length of time. 

On the other hand, the Marineland Magnum 350 can be used on this small tank, because of its twin valve taps, which enable the user to adjust the flow of water. And the Magnum 350 also has the micron cartridge which can be used to attach diatom powder to. In many respects it's the ideal diatom filter for tanks which have a fairly large footprint, yet are low in height.

And the 350 can usually be purchased for about $100 without the bio wheel, and for under $80 when the 350 is on sale. As is the case with the HOT 250, the 350 is a very cleverly designed and flexible filter to use. Just don't suck up sand in the unit, because you could end up seizing the impeller and burning out the motor. This is true in the case of both the HOT 250 and 350.

For the money though, you can't beat their performance. I recently purchased a few HOT 250s for $44.99 each at Doctors Foster & Smith, and got free shipping when I added a few items to get me to the $49 free shipping offer. The HOT 250 is a fine little filter, and a true bargain at this price. For that matter, so's the 350.


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