Good Morning, I have a question concerning the blue carbon filters in the Penguin 350's, 200's and 150's, all of which I use.

When I do my weekly water changes I take the carbon filters out of the Penguin unit and swish them around in the used water to get some of the gunk off(plant material, food, etc) and return to unit.

When do you know its time to replace with a new cartridge? Whats the approx. time frame of use or what do you watch for?

Thanks guys!

Hi. I use filters like that on one of my tank. The manufacturer recommends replacing the cartridge every two weeks becuase the carbon will be used by then... I have used it longer and found that the carbon really does stop working by about three weeks... but it depends if you are really using it for the carbon or the floss (the blue part over the carbon).

If it is for the floss, or mechanical filtration, then rinsing it as you do - in tank water - would be suffcient to maintain mechanical filtering as long as you know that the carbon is inert after a few weeks. In which case, you might as well save some money buying a big bag of filter floss and cutting it to the size of the filter pad rather than keep paying for the cartridges!

A nice advantage of having filter floos on hand is in the event of medicating the tank, or using certain additives, that charcoal absobs you will need to remove the charcoal filter pad completely. Then you can pop in a floss pad and continue mechanical filtration. Teh you can add the carbon again later to absorb the meds or whatever to reemove the additive from the water.

But, if you like to use the carbon for WQ, then I would replace it every two-three weeks if chemical filtration is needed/desired. (You can also use filter bags to hold charcoal so you can still use carbon but not have to buy the cartridges).

I don't know if that helped - but always skeptical of manufacturer's trying to make a buck - I tested the limit of activated charcoal and found it, indeed, to be limited. So, regular replacement of charcoal, maybe once a month, will be needed to keep it active... inmy experience.

Thanks Graham, can I ask how do you test the charcoal to see if its still good?

When my tank gets dirty!

But, here is a less lazy but simple method:


After doing that a few times, since you use the same cartridge each time, you get to knwo when to replace it regularly.

Thanks again Graham, I will do that ! So if I'm running two Penguin 350's on my 55 gal tank and I have two carttidges in each unit and the water appears yellow with the test you me to use, do I replace all four cartridges?

I'm sorry for so many questions, just want the best for my guys!

Thanks again!

Aha! Good question!

Since you will have two filters, and each one has two cartridges - you are in a nice position to rotate the cartridges so that you should never have brown water!

You could change two, one form each filter, every three or weeks. That way, if one of your filters goes kaput, you still have a "cycled" filter in the one and a fresh carbon.

Or you could change the two carbons from one filter at the same time for a while in order to see how long your carbons last... that way you can gauge changes.

I just take it in good faith that once a month is necessary - so, maybe you could get it all set-up and then test once a month, and if no brown, then you are on the safe side!

This is the same principle as the filter on Britta and other water filters. Becuse they are in even higher use, the carbon gets exhausted faster.

The 350s have bio-wheels, right?

As long as your tank is cycled, you don't need to keep replacing the carbon. Unless you like to have it as a fall back or spend the extra $ on it. Once the carbon has gone past a month, it's effectiveness is gone and needs to be removed from the tank. Otherwise, some of the harmfull things absorbed will start to leach back into the water. I cut a slit along the top of the filter with a scissors and dump it out. This allows you to keep reusing the filter pad for a VERY LONG TIME without having to buy anymore pads. Most of mine are now starting on year 3 of use with the original pad.

Thanks Graham and pm94! So let me address two thing.

First to Graham, yes the Penguin 350's have bio-wheels, two as a matter of fact. So I have a total of four bio-wheels in the 55gal tank. But what is brown water? I have never had it but you know I'll be watching for it now.

And for pm94, so once you pour out the carbon do you add more into the used cartridge?

You could add new carbon in if you wanted. But, like I mentioned before, once your tank is cycled you really don't need to have any in the tank. I've been without carbon for over 2 years in all my tanks. The only time you'd really need it after cycling is if you added some water meds that needed to be removed.

I never use Carbon very often myself.Once in a blue moon to get Meds out of a tank-maybe odors,but no-usually I don't use it. I only replace my filter pads when it gives me no choice(they're literally falling apart).I rinse them when I see that some water is blocked from coming out or the flow rate has changed completely--that tells me that they need rinsed in the next batch of tank water that I change out. This has worked for me for a very long time.

Thanks for all the replys! My tank is cycled so I guess "goodbye carbon" unless needed! I never knew that you could do this and really appreciate you guys explaining it to me.