New tank ammonia at 0.25ppm after 3weeks

I decided to upgrade to a 5x2x2 but kept my external filter which was well established running through a bucket filled with my old tanks water
Because I had sold old tank. Problem now is ammonia been at 0.25ppm for 3weeks and no trace of nitrite or nitrate ph7.6. I have alot of young malawi in their and ammonia never rises

How long did it run in the bucket? Just if theres no ammonia (fish waste or rotten food etc) to feed the bacteria it will eventually die and then ur pretty much back to square 1 or u might experience a mini-cycle at least

3days ,no heater in their either....

I cant imagine 3 days would do it too much harm but there's definitely something strange going on? Iv never experienced a mini cycle before im just going off what i have read. what sort of test kit are u using and how old is the test kit? how have your fish been since they've been in the new tank?

is your water totally clear?? im only askin this cos my tank is slight black water so unless there is a ton of ammonia in it the test wouldnt show as my water is yellowish brown anyway. just a thought

Yeah water is crystal and the test kit is API

all i can think is that ur bacteria in your filter has died and ur tank has gone into cycle mode again??? how often have u been doing water changes and has the ammo done ur fish any harm (any fish died or do any have any black on the gills)

what sort of filter are u using and how big was the tank that the filter came from? is the filter big enough to run on ur new tank? 5x2x2 is around 600Ltr so its going to need a pretty big filter

Its all pond solution 2000f , unsure of turnover but I will find out wen iget in from work.filter came out of a 70gallon

While your filter was running in the bucket it would have lost its bacteria quite gradually over 3 days. Especially with lower oxygen levels and the water being at room temp. So what your experiencing now is a mini cycle. At the moment with it being a Malawi set up with a high ph the ammonia is still toxic so keep an eye on that so it doesn't creep up any higher. I'd cut back on feeding till it rectifys itself. The main concern I see is the total lack of nitrite and nitrate. As these are not present it suggests a lot of progression needed by the filter to catch up. The bacteria that converts nitrite to nitrate must not be working or present and this is the bacteria that is slow to grow. As soon as nitrite starts to show though that's when extra care needs to be taken for the fish, especially as they are young, as nitrite is a lot more toxic than ammonia. What water changing have you been doing since it was set up?

25% per week

Am sure that does 2000 litres an hour which should cope just with filtration. I'd be looking for dead spots in your tank where there is little or no flow if waste food or poo is collecting in these spots they'll be releasing ammonia as they break down so you will always have a reading of ammonia in the water. Try using some coloured medicine drop straight in the flow of the outlet of the filter and watch it go round the tank the dead spots will take longer to get any colour in them. Easy remedy a powerhead or two to increase the flow pointing to the filter intake, test for dead spots again, then in couple of days check for ammonia.

What's your ph in tank compared to out of tap? I consider 25% a week to be very little. I'd up the volume if the ph's are similar. As for the ammonia and nitrite I'd keep checking it and if it gets any higher do a large water change straight away.

I have maxijet 1200 powerhead in tank also so theres alot of flow and agitation also ph is same in tank as tap

If the ph is the same I'd defo up the volume of water changed every week. As long as the water going in is a similar ph, hardness and temp then it will have no negative effects.

Just tested tap ph 7.6 tank ph7-7.2 I cant understand it. I have cobbles in their cud they be softening water?

The ph drops naturally in most aquariums. What type of substrate and rocks have you got? Also I assume they is no bogwood in there. Still that so t a big difference. I'd worry ic it was over 1.0 difference. For instance my ph drops to around 6.6 and I do a 50% change every 5th day with fresh water that is bang on 7 and it does no harm.

I have sand as substrate but gunna get some coral sand & ocean rock to buffer water thanks for the info every1 great help thenks