MARINA S15 Filter

I wonder at some filters too.

Does yours have the 'bio-carb' or 'bio-clear' catridges?

The bio-carb ones are meant for tropical tanks and Hagen says they contain carbon and

Ceramitek [which is] a highly porous ceramic biological filter medium, optimizes biological filtration

It sounds from that as though they do put a biological medium in the cartridge....and then tell you to change it every 2 to 4 weeks.

If you do have these cartridges, you do have some biological media so you have 2 choices.

1. Leave them there and don't change them. It's the carbon that needs changing as it gets full in a few days and stops working. But you don't actually need to use carbon. If you leave the cartridges there the carbon will get fulll, but it will also be colonised by bacteria. You will have to be careful if the fish ever get sick and need medication. There is a risk that whatever is on the carbon could get pushed off by the medication and that the med will stick to the carbon instead where it can't treat the fish.

2. If it is possible to make a small slit in the cartridge and empty out the contents, the best thing to do would be, one cartidge at a time, replace the contents with sponge. You would need to wait at least a month before doing another one so you wouldn't loose all your bacteria.


The same choices apply if you have the bio-clear cartridges. They contain zeolite and ceramitek. Zeolite absorbs ammonia, but it too will get used up and stops working. But like carbon, it can also absorb medication.



You say you have ammonia in the water. That builds up first as the fish secrete it, and nitrite won't appear until you have some bacteria to turn the ammonia into nitrite. Then that will build up until you have started growing the bacteria that eat nitrite, and nirate will then start to appear.
Until then, you need to do water changes every time you see a reading for either or both ammonia and nitrite. the water changes should be big enough and often enough to stop either of them ever getting to 0.25. With a reading of 2 for ammonia you need to do as big a water change as you can. Leave just enough water for the fish to be able to swim in. Test for ammonia again after 20 mins (to allow the new and old water to mix) and if it's still above 0.25, do another massive water change.
Four weeks should be long enough to have grown at least some ammonia eating bacteria. It seems unusal that you have no nitrite yet. Can I ask how you are testing the water - strips, liquid tester or the shop does it?

The other thing I'm wondering about is that you have guppies, a dwarf gourami and shrimps still alive. Those fish are notoriously sensitive to bad water conditions and shrimps are usually more sensitive than fish. Is there a possiblilty the ammonia tester is not accurate/not working properly?




Just one last thing - once you have the ammonia (and later possibly nitrite) sorted, you need to look at your fish. You have only one cory and they are shoaling fish. But a 60 litre tank isn't big enough for 6+ bronze cories. Maybe think about part-exing it for a shoal of one of the dwarf cory species - pygmy cories (Corydoras pygmaeus), panda cories, Corydoras habrosus or Corydoras hastatus. Six of one type, not a mixture.

Are the cartridges the same as most I've come across - that is, are they like a bag fixed to a frame with the carbon and ceramitek or zeolite and ceramitek inside the bag?
If they are, the bag will hold some bacteria and so will the ceramitek. What people with this bag style cartridge do is cut a small slit near the frame and empty out everything inside. Then depending on how big the cartridge is, either cut thin slices of sponge or a big piece of sponge and push it in through the slit, carefully so you don't tear the bag. The sponge can be any make of filter sponge. With the carbon ones, it might be possible to see black and white bits from inside the cartridge. The black will be carbon and the white will be ceramitek. If you can separate the black and white bits, you can put the white ones back in and fill the left over space with sponge. This won't work with the zeolite bag as zeolite is white too.
But don't do all the cartridges at once. Do one, wait a month and do the next, wait another month and do the third.

It is also possible that your cartridges have layers of a fabric style substance and the carbon, zeolite and ceramitek are impregnated into the fabric. This would be more difficult to alter.


If you have only just put the zeolite cartridge in the filter that will be absorbing some ammonia. The danger with zeolite is that it can fool you into thinking that the ammonia level is going down because the filter bacteria are growing. But zeolite will get full and stop absorbing ammonia; and if there aren't enough bacteria the ammonia level will go up. If you use zeolite you are tied into changing the cartridges before the zeolite gets full for ever.

You could always leave the carbon cartridges in the filter permanently but I would be inclined to swap the zeolite cartridge for another carbon one. If it's only been in a few days it won't have many bacteria in it yet, so now is the time to swap it.


The API test kit is fine. If possible, look at the ammonia test in daylight as fluorescent lights or energy saving bulbs can distort the colour.
I have some amano shrimps, they do like to hide. You will know if they die because you'll find them on the bottom of the tank pink like cooked prawns. They also shed their skins to grow so if you see what looks like a see-through white shrimp on the bottom of the tank it is a shed skin.

The symptoms of ammonia poisoning are - fish rubbing themselves on something, fish gasping air at the surface, very red gills. They also gasp at the surface with nitrite poisoning. And fish that are unhappy for any readon could keep their fins clamped up next to their body, huddle in one corner, not eat any food, not be able to swim properly.
It sounds as though none of your fish are doing that, which is why I thought I'd better check how you were testing ammonia in case it was a false reading.

The safest thing to do for now is water changes every time you see a reading above 0.25 for ammonia and/or nitrite.