10 Gallon Tank Cycling with an old filter - yet ammonia won't go down?

Hey everyone! I have 2 established tanks - a 55g, and a 20g. Recently I saw a good deal on a 10g kit, and well, you know how it is - what's one more tank?

My 20g has been running two filters for about 9 months - a 10g HOB filter and a 20g HOB filter. So as I was setting up my new 10g tank, I took the established filter media cartridge out of the old 10g HOB filter and put it in the new one (and the new filter media cartridge in the old filter). I also had some extra sponge hanging around in my 55g, and I put that in the new tank as well (right beneath the filter). Then I took the intake sponge from my 55g tank and squeezed all that brown sludge into the new 10g tank as well. This is going to be my new quarantine/hospital tank, so I put no substrate in, only some plastic plants and two pieces of driftwood (also taken from my established tanks). Water temp right now is about 82.5 degrees. When I filled the tank, I used 50% water from my 55g and the rest fresh, conditioned water. I then added ammonia up to around 3ppm. It's been 8 days, and the ammonia has not gone down. Nitrites are zero. PH is between 7 and 8. I thought that by using the old, established filter, it would basically be almost instantly cycled? Was I wrong? Since it's a hospital tank, I thought that's what I would do if ever needed? Just pop an old filter in and have it ready to go for emergencies? Does anybody have experience with this? Thank you!

to make it easier to read, here's a summary of what's in the new tank
. new 10g HOB filter with old filter media cartridge
. old sponge from the 55g under filter
. intake filter squeezings from the 55g
. 2 pieces of driftwood from established tanks
. 50% water from the 55g
. water temp at 82.2
. ph between 7 and 8

 

My advice is just always have some substrate. The amount of surface area it provides for long term bacteria growth is too valuable to skip. A single HOB cartridge probably wont do much.

 

Yeah you were wrong. 3ppm ammonia is A LOT.

The media you used can only handle the ammonia load that was on the tank it came off of or less, not more. To handle more it will need time to multiply and size up the colony.

Your filter is cycled, it's spiking and holding ammonia because you've overwhelmed the colony you have currently and it can't process all of that.

Ideally if you wanted to test it, you use maybe 1ppm ammonia, but people that have Jumpstarted tanks before generally just trust it and don't do what you did and test it. They just move the media and lightly stock immediately.and if no spike after a week can go up to the stocking level of the previous tank.

If you fishless cycled previously, and then stocked, whatever ammonia you used to fishless cycle was likely much more than the ammonia your fish produced and the colony died off to what is sustainable over time, i.e. the stocking level the media came off of.

Rough estimate, 5 or 6 pounds of fish eating high protein is roughly 3ppm ammonia in 24 hours. 3ppm ammonia is a lot of ammonia that most tanks never see. Most tanks are under 1ppm created and processed in 24 hours.

Hoping this makes sense how I explained it. It's too much ammonia for your bacteria colony to handle and they are like, "oh heck no, we can only eat so much dude! Strike strike strike!" Water change the ammonia down to 1ppm or get rid of it all and redose to 1ppm, and wait for the colony to get back to work with something they can deal with.

 

Hi!
Good advice above. the other thing I would mention is the use of old tank water. You're really only moving over nitrates and water depleted of natural minerals found in tap water

 

Yeah you were wrong. 3ppm ammonia is A LOT.

The media you used can only handle the ammonia load that was on the tank it came off of or less, not more. To handle more it will need time to multiply and size up the colony.

Your filter is cycled, it's spiking and holding ammonia because you've overwhelmed the colony you have currently and it can't process all of that.

Ideally if you wanted to test it, you use maybe 1ppm ammonia, but people that have Jumpstarted tanks before generally just trust it and don't do what you did and test it. They just move the media and lightly stock immediately.and if no spike after a week can go up to the stocking level of the previous tank.

If you fishless cycled previously, and then stocked, whatever ammonia you used to fishless cycle was likely much more than the ammonia your fish produced and the colony died off to what is sustainable over time, i.e. the stocking level the media came off of.

Rough estimate, 5 or 6 pounds of fish eating high protein is roughly 3ppm ammonia in 24 hours. 3ppm ammonia is a lot of ammonia that most tanks never see. Most tanks are under 1ppm created and processed in 24 hours.

Hoping this makes sense how I explained it. It's too much ammonia for your bacteria colony to handle and they are like, "oh heck no, we can only eat so much dude! Strike strike strike!" Water change the ammonia down to 1ppm or get rid of it all and redose to 1ppm, and wait for the colony to get back to work with something they can deal with.

Ha! Yep, I guess I was wrong. Every time I think I finally know stuff about this hobby, I find out I really know nothing
Thank you for your detailed explanation! I have always done fishless cycles and started at 3ppm ammonia so I stuck with what I knew. I'll do a big water change and get it down to 1ppm and then go from there.

 

One tank's filter may not actually be enough to cycle another. If you had a 10 gallon filters in a 20 gallon cycled tank and added media from a 55 gallon cycled tank but both tanks have light stocks, you might've not added enough seeded media to jump start the cycle. As SparkyJones said, filter media only has enough beneficial bac to kick start a tank of the same size and stock. If I add a 50 gal filter into a 20 but the 50's heavily-planted and understocked while the 20 is lightly planted and heavily stocked, it wouldn't cycle as there wouldn't be enough bacteria to do the job.

Whatever the case, maybe the filter and media isn't enough. Now the tank's going through a mini cycle.

Just do what you do to cycle tanks and it'll be good in a few weeks

 

One tank's filter may not actually be enough to cycle another. If you had a 10 gallon filters in a 20 gallon cycled tank and added media from a 55 gallon cycled tank but both tanks have light stocks, you might've not added enough seeded media to jump start the cycle. As SparkyJones said, filter media only has enough beneficial bac to kick start a tank of the same size and stock. If I add a 50 gal filter into a 20 but the 50's heavily-planted and understocked while the 20 is lightly planted and heavily stocked, it wouldn't cycle as there wouldn't be enough bacteria to do the job.

Whatever the case, maybe the filter and media isn't enough. Now the tank's going through a mini cycle.

Just do what you do to cycle tanks and it'll be good in a few weeks

I have Kickstarted my 72g off my 20g just using the 10g of water and the filter media. But I knew at best I could only stock for what the 20 gallons had tops but more like 10g at first to be safer. I don't think the water move was really necessary, as much as I've read into it at best maybe 15-20 % of the aquariums bacteria is in the tank on an aged tank that long been cycled, and 80+% is in the filter media where all the oxygenation and water movement is.
That last 15-20% just doesn't matter much, the 80% or so you move with the filter will multiply in the next 24 hours and catch up to full speed.

Lately I'm just using sponge filters and just move a sponge to take my 10g in and out of service and I've never had an issue with immediately stocking it full going from bigger fuller tanks to the 10g.

I really think the misstep here was crushing it with the 3ppm ammonia to test it. If the filter and cycle works on another tank it will work just as well as it did there, on a new tank all things being equal.

If that filter was doing like .5ppm ammonia in 24 hours or less and you moved it, it's just not going to be able to handle 3ppm any time soon. 6-12 days, maybe even longer depending on what it was doing. Bacteria likes constant and stable, a fast shot to 10x what it can handle can stun the colony to a crawl and have it focusing on reproduction rather than consumption where it racing to keep up, old is starving off and new is popping up but it's not growing in size or gaining any ground on the ammonia pile.

I would water change that ammonia down or even out of the tank then redose a much smaller amount.or just move one fish for a week and see if it gets back on track, at least it limits losses. 1 fish and 10g is easy to keep safe, to water change and cycle through if you have to but I think when the ammonia comes down the colony will get back on track and consume and reproduce again as normal.

 

I really think the misstep here was crushing it with the 3ppm ammonia to test it. If the filter and cycle works on another tank it will work just as well as it did there, on a new tank all things being equal.

Ah, I didn't realize you did that. Apologies. Looks like you stalled the cycle or maybe even killed off some of the bacteria. They can take on a lot of ammonia if they're used to it, but even too much ammonia can kill the bacteria, or at the very least make them go dormant

 

It normally takes at least three weeks for the nitrifying bacteria to build up to the point that it will convert 2ppm ammonia in a period of 24 hours. You did use seeded filter media, which is good, but a filter media cartridge has limited surface area for bacteria to colonize. Sponges and filter pads have a lot more surface area.

In your old tank, the biofilter was distributed among your substrate, tank walls, plants and decorations, and two filters. While the cartridge in the 10 gallon filter might have contained bacteria, it would not have been enough to handle 3 ppm ammonia. Do not add any more ammonia until the ammonia drops to zero and you start to see nitrites or nitrates start to rise. Since you already have some bacteria that convert nitrites to nitrates, you might not see a spike in nitrites, but then you might.