25percent Water Changes Why This Amount ?

Hi,

I think the ~25% weekly change is usually advocated because that's what people generally find is needed to keep their ammonia and nitrite at 0ppm and their nitrates under 20ppm. It is my understanding that too large a water change (esp over 50%) could risk causing a mini-cycle / loss of too much good bacteria in the process, although someone else may be able to confirm if this is the case. If you were finding difficulty in keeping water at the levels of ammonia and nitrite at 0ppm and nitrates under 20ppm, then larger and/or more frequent water changes should address that, so that's why it's so important to monitor those weekly just before a water change so that you know what they tend to be - and monitor more frequently if you make any changes to the tank such as add fish, feed something different, do smaller/larger water changes, add/remove filter media, etc.

By biofilm (which is generally good ie the good bacteria which is on the internal sides of the tank and on the decor), do you actually mean the slightly oily look on the water surface? If so, this is more likely a build-up of fats (etc) from the food. If you don't like it, you could always do two water changes per week.

Be careful about changing the filter media - filter companies often recommend this despite it being unnecessary, and it can induce a mini-cycle (and therefore ammonia, nitrite and nitrate spikes). Although it does recommend splitting those, the key rule of thumb with changing filter media is not to change more than 30% at a time and generally to leave about a month between any further changes to give the good bacteria a chance to re-grow/build up. If the sponge isn't falling apart (just stained), then I would not change it but simply just gently  squeeze it in old tank water, to avoid losing too much bacteria. If/once it's at the stage of falling apart, then you could consider cutting it and removing/replacing a third of it, then perhaps in a month's time, removing/replacing a third of the ceramic media, etc.

If you let us know what filter you have, though, we may be able to advise further and more specifically. I have the Marina i110 filter (take a look at it to see if it's similar to yours), and it only allowed the complete replacement of the cartridge, not a partial replacement, so I ended up converting it over to purely sponge media which has made it a lot easier. If yours is similar, I can advise in more detail how to go about that.

I too never change my media. I have sponges which I squeeze in tank water taken out at a water change, and Eheim substrat pro, sintered glass balls this company uses instead of ceramic media, and I just swoosh the baskets up an down in old water.
Some small filters have cartridges made of a sort of fabric on a frame with carbon inside. Carbon gets full after a week or two which is why that does need replacing - but as you don't actually need carbon, if you have one of these in the filter the best thing is cut a small slit in the 'fabric', empty out the carbon granules then stuff it with sponge. Then just squeeze the debris out in old tank water.

Hi
Meant to say yes its oil on the surface .
Ally

I have a couple of those small air pumps, and would certainly recommend them as they are so quiet compared to others.

In the second image in the Amazon link it shows the pump with a wire going out the bottom which has the plug on the end.  Coming out the top is the air line tubing - in the background you can see the tubing (only) then goes into the tank with the air stone on the end.

Does that help?

Yes it is. The air stone in the links is a small ball, the ones in big tanks are a long strip which need a more powerful pump to run them.

You wouldn't need to run the airstone full time, Matt suggested using a timer to turn it on for 15 to 20 mins after feeding to break up any oily residue from the food.


As a side point, air pumps can be used to power sponge filters which are very suitable for bettas and fish fry. Earlier this year I swapped the internal filter in my betta's tank for an air pump powered sponge filter (cycled it first in the quarantine tank) and I am very pleased with it, and the different way my betta now behaves.

Hi all
Well I got a small air stone and set it up , but I think it's too bubbly for my small tank ! It's breaking up some plant leaves and stirring up the dirt !
I may just be putting it on as Matt suggested after feeding for 15-20 mins . It's wreaking my peacefull tank ! Moonbeam is not a happy boy !
Also got the root tabs and the hikari bio gold betta pellets .
Ally😥

You could try piercing the part of the hose that's outside the tank to reduce the flow of air at the stone... Or if you could buy a splitter you could leave one output open to atmosphere which would drastically reduce the flow of air to the stone...

There's always more than one way to fight a fire 

Hi
All the man in the shop said there is a clip that you put on the tube that squeezes it to reduce the flow , so I can get that online if I could remember the name of it .

That'll be this.

Hi Sue
Can I ask where you got the valve ?
I have been using the air stone after feeding but now it's caused really cloudy water ! I have never had cloud water since I set up the tank ! I did a water change yesterday but now feel I've got to do another . It must be something to do with the stone !
I've removed it now . Why has it done this ? Is it going to harm my fish ?
Ally