I know that I should rinse my filter cartridge whenever I clean my tank (in tank water of course), but how often should I actually change the cartridge for a new one?

Most of us rinse the cartridge when the water cannot go through anymore or slow down. We also change it when it is completely damage.

Take a look at the following url for detail explaination
http://www.kokosgoldfish.invisionzone.com/...showtopic=26495

heres some good advice change it when it wants changeing lol
i change it every 8 weeks

In general, you should clean the cartridge every time you change the water. Take it out and bang it out well in the bucket of used water. I have such heavy cycles built in my tanks that I do not rely on the cartridge for any beneficial bacteria, so I take my cartridges to the utility sink and blast 'em clean with a high power spray. (I also have unchlorinated well water!)

A cartridge carries a heavy load of waste and mulm - even though it may still have sufficiant flow - or appear to have good flow. If you remove all this extra waste, it is that much less that your cycling bacteria has to convert to nitrate - and that much less you have to remove from the water during changes!

My cartidges are only replaced when they are literally falling apart - about once or twice a year! They really do not need it much beyond that. If you have cartridges that contain carbon, after about 2 weeks, the carbon is "full" and can bind no more impurities from the water. AT that time, you have a choice of leaving the carbon in place, where it will act as a platform for beneficial bacteria, or slitting the cartridge and banging the carbon out into the garbage. You can then leave the cartridge "empty" or refill it with more carbon or even pieces of ceramic media or some such other platform for beneficial bacteria.

Lol what daryl said. Just keep using it till it can't be used no mo' !

Sounds good. Thanks for the advice!

ye sorry daryl i started to read what you typed but got bored sorry
use it till u cant use no more only if youre tank is more then 60liters

I'm not sure if I understood what you meant; but I think all setups should include some type of filtering. Even small setups such as 1-gallon bioOrbs make use of an undergravel filtration unit -- which is, of course, NOT good for fish as large as goldfish, but can be doable for other fish such as a betta.

In my younger brother's aquarium, he has a pet betta and we use a sponge-filtration unit that uses an airpump to circulate water through the sponge. It's cheap and easy to maintain and works well as a platform for nitrifying bacteria.

Without some type of filtration you run the risk of the water running stagnant between water changes.

Anyway, I agree with Daryl. Your filter is the #1 source of nitrifying bacteria and your filter media the heart of that source. Only change when the media is in tatters, otherwise, just get the mulm off running fish-safe water through the media or banging it against a bucket full of fish-safe water.

Never mind - most intelligent people are adept at soaking up useful information so boredom is never an issue with them ....

Undergravel filters especially in small tanks are a PAIN. lol. Just plant some low light requirement plants in the tank and you should be fine without any filtration. Plants love ammonia and my plants keep my water so clean that I only do water changes every week and only 50% on my one and two gallon tanks.

Edited for language

Im sorry but plants dont love ammonia they use up nitrates in the tank, expelling o2 in the day and at nite dioxide. So if you place to many plants in the tank with no water movement for O2 to get in the water, you could suffocate the fish.

Not to mention that when there is not enough light, plants tend to go through oxidative metabolism in order to continue living and thereby use O2 in the water! Scary thought.

Really? Hmmm.... according to what I've learned planted tanks do really well without filtration.....at least the small ones....O.o Someone told me that plants love ammonia but I guess they're wrong. I'm sorry for giving bad advise! I should make sure I really learn it first. Thanks for setting things straight guys.

Edit: I checked back from the site and it said that plants take well to using ammonia... oh well......must be wrong.

Well plants do well with out water movement in the tank, the problem is that at nite the goldfish need the water movement cause the plants take up the O2 in the water and suffocate them. So that part your right.

As for plants using ammonia, they might in a tiny amount but the thing is aquatic plants use the nitrates to live off of and lighting. So you will need good lighting too.

Anubias plants dont need as much and would do fine with just 2 watts per gal, but most of the other plants like much more than that, then you have to look at your PH, KH, and GH cause some plants like hard water some like soft, some acidic water and non......

anywho

I want to see the site! I personally have never see NH3/NH4+ uptake with plants. I've always see the nitrogen cycle as NO3 taken up by plants. Maybe it depends on the plant?

I'll put up the site as soon as I can. I have it in my list of bookmarks but as my profile says I'm a master procrastinator so I need to get lots of homework done lol. It was called a goldfish aquarium board or gab and it was an article about walstad natural planted tanks.

Edit: Lol it's at the top of my bookmarks. Heres the link. http://thegab.org/Articles/WalstadTank.html
Hm....maybe I read it wrong? Oh.....I think I read it wrong. It is good but probably wouldn't work for goldfish as goldfish scavenge around the floor.

Here's the link I used to set up my betta tank. http://thegab.org/Articles/NPBettaBowl.html

Here's a link from the betta article that says plants prefer ammonium of nitrates. http://www.aquabotanic.com/plants_and_biol..._filtration.htm

Hm, it seems to depend on the plant, but I'll have to look into it when I have more time. Very interesting! Thanks for the links!

I think the majority of plants prefer ammonium while only a few prefer nitrates. Anyways, no problem.

If I may add my 2 cents also, when I set up my planted tropical tank, I put the plants in first, then added the fish a couple of days later. I never got an ammonia reading and it was 2 or 3 months, after the guppies had multiplied several times, before I was able to detect any nitrate. It would seem that my plants were taking in the ammonia or the nitrate before it could build to detectable levels.