I have a 20 gallon aquarium with 2 angelfish, 2 gold dust mollies, 2 black mollies, 2 guppies & 1 red tailed black shark. I setup the tank september 30th of this year. I let it run without fish for about 1 week. I checked ph, ammonia, nitrite & nitrate. Ph was slightly alkaline 7.2ish and the other 3 tests read 0 ppm. Anyway the fish are swimming around and eating with no visible signs of issues. I have a bio wheel hang on filter which is working great and I change filter cartridge when it starts to overflow over top, I also have plenty of aeration (an air stone on one side of tank and a volcano on other)The temperature is 78f all the time. I don't over feed and do weekly 25% water changes. My ph & nitrate read 7.0(ph) & nitrate is 0ppm. My ammonia is .25ppm & nitrite is also .25 ppm. I am baffled on whats causing this. I purchased my fish in october & early November on separate occasions(at least a week apart). Except the one time where I bought: male guppy, 2 black mollies & red tailed black shark the same time. Am I in danger with my water quality of losing fish? What should I do?
TOTALLY BAFFLED & FRUSTRATED
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Lajos_Detari
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You don't change your filter unless they are breaking apart.
Each time you change your filter, you are restarting your filter from zero as you lose all the beneficial bacteria in the filter.
I advise you to use normal sponge pad as your filter media instead of the cartridges that have carbon and need to be replaced every now and then.
Just buy some sponge pads and cut them to the right size to fit into your filter compartment.
www.aquariumcoop.com
I think you also have overstocked your tank and your water change is too little.
What are the sizes of your fish?
Angels can grow very large.
Mollies and Red tail shark are also too big for your tank when they grow to adult.
Your water change each week need to be at least 50%.
Each time you change your filter, you are restarting your filter from zero as you lose all the beneficial bacteria in the filter.
I advise you to use normal sponge pad as your filter media instead of the cartridges that have carbon and need to be replaced every now and then.
Just buy some sponge pads and cut them to the right size to fit into your filter compartment.
Coarse Sponge Pad | Aquarium Filter Media to Trap Dirt and Debris
Don't use the disposable cartridges in fish tank filters. Replace them with reusable aquarium filter foam to mechanically filter particles from the water.
www.aquariumcoop.com
What are the sizes of your fish?
Angels can grow very large.
Mollies and Red tail shark are also too big for your tank when they grow to adult.
Your water change each week need to be at least 50%.
You don't change your filter unless they are breaking apart.
Each time you change your filter, you are restarting your filter from zero as you lose all the beneficial bacteria in the filter.
I advise you to use normal sponge pad as your filter media instead of the cartridges that have carbon and need to be replaced every now and then.
Just buy some sponge pads and cut them to the right size to fit into your filter compartment.
I think you also have overstocked your tank and your water change is too little.Coarse Sponge Pad | Aquarium Filter Media to Trap Dirt and Debris
Don't use the disposable cartridges in fish tank filters. Replace them with reusable aquarium filter foam to mechanically filter particles from the water.
What are the sizes of your fish?
Angels can grow very large.
Mollies and Red tail shark are also too big for your tank when they grow to adult.
Your water change each week need to be at least 50%.
Attachments
Hi so I think your problems will stem from when you started the tank and let it stand for a week even though you had zero ammonia then that’s because you had no Ammonia source then when you added fish the ammonia appeared and your bacteria colony will have started to grow to deal with it now you are at a few weeks in you are likely over the worst of the cycle and your fish fortunately seem to have e survived. As mentioned above too removing anything from your filter will cut down your colony so it’s best to Gently clean them in a bucket of tank water and put them back in.
it’s probably worth mentioning that some of your fish will outgrow a 20 gallon tank so you might want to address that at some point
it’s probably worth mentioning that some of your fish will outgrow a 20 gallon tank so you might want to address that at some point
The members
I tried posting videos but couldn't
So the carbon filled filters are not as good as just a plain foam filter?You don't change your filter unless they are breaking apart.
Each time you change your filter, you are restarting your filter from zero as you lose all the beneficial bacteria in the filter.
I advise you to use normal sponge pad as your filter media instead of the cartridges that have carbon and need to be replaced every now and then.
Just buy some sponge pads and cut them to the right size to fit into your filter compartment.
I think you also have overstocked your tank and your water change is too little.Coarse Sponge Pad | Aquarium Filter Media to Trap Dirt and Debris
Don't use the disposable cartridges in fish tank filters. Replace them with reusable aquarium filter foam to mechanically filter particles from the water.
What are the sizes of your fish?
Angels can grow very large.
Mollies and Red tail shark are also too big for your tank when they grow to adult.
Your water change each week need to be at least 50%.
Attachments
I use both. Once the cartridge filter (with carbon removed) begins falling apart, I move to sponge filters. This happens after about a year of use from cartridge filter. Just swish your filter media in a little tank water every 2 weeks when cleaning tank and that’s all you need to do. No need to replace them until they begin falling apart.
I'm sorry I'm alittle confused. So I shouldn't "just use" the foam filter? The ones I have already are filled with carbon(above pic). So should I use both simultaneously? Also my nitrite & ammonia levels are they dangerous?
You can cut the bottom of your filter cartridge and remove carbon. Then use cartridge. The carbon is only good for a couple of weeks. Your numbers should always be 0 ammonia, 0 nitrite, and less than 20ppm nitrate. If any higher, do a large water change. If you do a 50% water change then you reduce your numbers by 50%. Hope this makes sense. Ask anything you need. 
Lajos_Detari
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Yes, you are right.
Firstly, carbon are not a good media for the beneficial bacteria (BB) to grow on it.
Secondly, carbon may also absorb the minerals in the water that are require by the fish.
I only use carbon when I want to remove the medication in the tank after treatment with medication.
Thirdly, if you don't replace the carbon after a few weeks, it will leak whatever it absorb back to the tank.
Foam or sponge has big surface area and full or pores which enable more BB to grow on it.
The bigger the surface area and the more pores it has, the better it is.
Water can easily flow through the pores and be in contact with the BB.
This allows the BB to convert the ammonia to nitrite and nitrite to nitrate.
AbbeysDad
Fish Gatherer
You didn't cycle the tank. Cycling refers to the nitrogen cycle that builds sufficient beneficial bacteria to process (cycle) ammonia (nitrosomonas) and nitrites (nitrospira) into nitrates (and nitrates we keep low with routine partial water changes).
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I'm also not a fan of cartridge filters and as mentioned you could hot rod yours to use sponge material instead...or as mentioned, slice the bottom to remove the carbon and keep using the same cartridge until it nearly falls apart (just rinse well with tank water @ every water change).
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With your stock level, I'd suggest about a 50% weekly water changes, but until you get the ammonia and nitrites under control, you may need to do daily or every other day partial water changes to protect your fish. You might also use Prime to neutralize the ammonia until bio-filtration kicks in.
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I'm also not a fan of cartridge filters and as mentioned you could hot rod yours to use sponge material instead...or as mentioned, slice the bottom to remove the carbon and keep using the same cartridge until it nearly falls apart (just rinse well with tank water @ every water change).
---
With your stock level, I'd suggest about a 50% weekly water changes, but until you get the ammonia and nitrites under control, you may need to do daily or every other day partial water changes to protect your fish. You might also use Prime to neutralize the ammonia until bio-filtration kicks in.
Last edited:
DAnCSF
Fish Crazy
Hello,
Welcome to the nuances of fish keeping...among which is cycling tanks, and methods to remove ammonia. For some situations, you can remove ammonia via mechanical/chem (i.e. filter cartridges w/activated charcoal)., or you can go all biological route, and to make it all the more confusing you can do a situation hybrid method with both....I can only suggest that you keep reading the forums and decide what method fits your tanks. And as always keep asking questions, lots of good people here to help.
Welcome to the nuances of fish keeping...among which is cycling tanks, and methods to remove ammonia. For some situations, you can remove ammonia via mechanical/chem (i.e. filter cartridges w/activated charcoal)., or you can go all biological route, and to make it all the more confusing you can do a situation hybrid method with both....I can only suggest that you keep reading the forums and decide what method fits your tanks. And as always keep asking questions, lots of good people here to help.
If you use live plants, about 30-50% of the volume of your tank most of those problems will go away. I think your tank is over stocked so the live plants will help to keep it stable and will also give the fish protection from each other.
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