Zoo Med 501 Filter review

December 29, 2007 at 6:58 pm 8 comments

I’ve been using the Zoo Med 501 filter for several months now and here’s what I think about it:

Overall: a good ‘first’ filter for small turtle habitats. The filter will eventually need to be replaced with a stronger, bigger filter when the turtles grow and the habitat is upgraded to a larger size.

Strength: Rated for up to 30 gallons of water with a max flow rate of 79 gph (gallons per hour). The max flowrate is the rate that water is pumped through the filter without any filter media. The circulation rate would be the rate with the filter media actually installed. It’s typically about 80% of gph, so flow rate would be roughly 63 gph (79 x 80%). This means that for 30 gallons of water, it will circulate all the water just twice (63/30 = 2.1). Not bad…but for turtles circulating all the water 3 times or 4 times would be more preferable, but twice isn’t bad.

Filter media: Comes with all the media you need and is ready to use right out of the box. It comes with a sponge (mechanical media), a carbon bag (chemical media), and ceramic rings (biological media). Carbon isn’t really needed in a turtle tank, but if you really wanted to continue using it, it would be cheaper to buy your own carbon than to keep buying the Zoo Med branded carbon packs. I prefer to ditch the carbon and just use more biological and mechanical filter media instead.

Noise: It’s a quiet filter. You’ll hear it running if you’re right next to it, otherwise you won’t hear it at all. The waterfall sounds from the spraybay can be avoided by putting it underwater or by aiming the water to spray right on the wall of the aquarium.

Complaints: My main gripe with the filter is that you don’t have much flexibility with how to arrange the media. The canister is divided into two parts, one for the biological and chemical media and the other for the sponge with the water flowing only in that direction. Because of the design, you can’t adequately have the water flow through the sponge first (which makes the most sense) then through the other media next. Because the water will flow through the carbon or rings first, the filter will clog a lot quicker than it otherwise would.

By the way: there is no right/wrong order in inserting the carbon and ceramic rings. They each filter out different things from the water and it doesn’t really matter which one cleans the water first. In the case of this filter though, it would be better to keep the carbon on the bottom and the rings on top. Doing it the other way around will only make the filter clog quicker.

My experience: I’ve used this filter for two RES turtles for when they were hatchlings to about 2.5″ in a 5.5 gallon tank starting with 1 gallon of water which slowly increased to 4 gallons of water. It has done an excellent job. It isn’t strong enough to suck most of the debris out of the water, but it keeps the water looking clear and clean. Spot siphoning everyday or so is needed to keep the tank looking clean. The spray bar does a passable job of providing surface water agitation in a small aquarium but isn’t enough to remove the oil film that forms. All the ammonia and nitrites are completely removed from the water with the filter, but with two turtles a weekly 100% water change was needed, as nitrates only took a week to get to 40ppm. The filter can get clogged fairly easily, so I usually clean the filter media every time a water change is done. Also, the tubes accumulate algae and dirt fairly quickly. It is very easy to prime (start), and will even start even if the canister isn’t completely filled with water.

I will continue using this filter in the small tank long after the turtles have been moved to a much larger tank. It did a good job with the turtles and I’m positive it will do an excellent job with fish and shrimp.

Mar.19, 2009 Update: I’ve made an updated review of the 501 filter. See it here: 501 Zoo Med Turtle Filter review, appended.


Entry filed under: equipment, habitat.

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8 Comments Add your own

  • 1. sep  |  April 12, 2009 at 6:47 pm

    what filter do you recommend for two 7″ sliders in a 65 gallon tank? I have two 501’s at the moment but they are doing a terrible job. The tank NEVER looks clean. any suggestions? Thanks

  • 2. forlogos  |  April 14, 2009 at 1:24 am

    based on my experience, I’d say a Filstar XP3 would be best.

    Any filter will not be able to pick clean out all the dirt in a tank…you’ll have to spot clean it at least once a week – and remove any uneaten food and poop!

  • 3. Micaela Stewart  |  July 2, 2009 at 2:36 am

    I inherited a turtle for my classroom, it has the zoo med filter bu and it has been problematic the last few months. It seems tempermental an d sometimes will run without sucking any water until the middle of the night. Currently mypoor turtle hasn’t had a filter in the last 2 weeks. Any suggestions

  • 4. forlogos  |  July 2, 2009 at 3:53 am

    usually filters will do that if they are clogged. Step 1 would be to make sure that the filter media is clean and that water can run smoothly through it.

    If it’s the case and it gets clogged too quickly, then its time to upgrade to a bigger filter. If not, then perhaps the old filter has reached its end and a new replacement filter is in order. Bigger is always better.

    In the meantime, I would do more water changes to ensure that your turtle is living in good water.

    Hope things go well!!

  • 5. caity  |  September 7, 2009 at 2:38 am

    This filter killed my turtle. I woke up this morning to find her lifeless. I will never use this filter again. I hope to save someone from this experience. It is heartbreaking.

  • 6. forlogos  |  September 7, 2009 at 5:06 am

    I hope you are feeling better, condolences…

    This kind of accident can happen with any filter, so it’s very important to take precautions that pets don’t get stuck in the first place. Was the filter strainer in place when this happened & how big was your turtle? Your experience can certainly help us all if we had more information to share with everyone.

    Again, very sorry for your loss Caity…

  • 7. Urbane  |  November 20, 2009 at 10:30 pm

    I have a 501 filter in a 20 gal and its half filled. Its ok for now, but my turtle is like 6″ and if I dont constantly clean around the tank every other day or so…the filter sponge will get clogged and the water gets dirty.

    I don’t see how it claims to be able to keep the water sparkling clean and 78 gph? Then the tubes get algae in them and really clogs the system. It does an okay job moving some of the larger debris, but I also have to add cloud water treatment so the particles can come together.

    • 8. forlogos  |  December 21, 2009 at 5:26 am

      IMO your turtle is too big for the filter – I can see how shed skin and other turtle waste can quickly clog up the filter. You need a stronger filter.

      Filter aside, your turtle is too big for just 10 gallons of water – even if you had a more powerful filter, the water quality you would have would require frequent water changes.


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