55 Gallon Tank Not Cycling?

  • #1
I have a 55 gallon corner tank which doesn't appear to be cycling. Back in July, we grabbed some filter media from a well established tank from a local aquarium Facebook group, and my understanding was that to keep the bacteria in the filter media alive, we would need to add fish so that it would have a constant supply of ammonia, so we added some fish at the same time (5 zebra danios, 3 guppies, 3 platys, 6 khulI loaches).

I have been keeping an eye on the water parameters, and they basically haven't changed at all since then...ammonia stays around 1 ppm, nitrates and nitrites are a firm 0, pH stays around 8. I do weekly 25% water changes, my tap water has 0 ammonia/nitrates/nitrites, and a pH of about 7.5. Correct me if I'm wrong, but should I not have a nice little colony of bacteria producing nitrites/nitrates by now?

Curiously, I have a 10 gallon tank that was set up around the same time, and through a series of events that I now know to be total n00b mistakes, it started its cycle at the same time as my 55 gallon...and it does have nitrates showing up on the test. There is just a lone pleco in that tank (it's a long story...don't ask).

I do occasionally trade some filter media between the tanks to try and kick-start a bacteria colony in the large tank, but it doesn't seem to be working.

What am I doing wrong?
  • #2
I would venture to say too many fish added at once. Even with cycled media it would be advisable to add just one group of those fish then gradually add to the numbers. Hind sight is always 20/20 as they say. Unfortunately I’m dealing with a fish in cycle as well with negligible experience. Best of luck and continue to post your progress.
  • #3
Have you made sure your tap water doesn't have ammonia in it?

You didn't mention whether the 10 gallon has ammonia or not.
  • Thread Starter
  • #4
10 gallon has 0 ammonia, 0 nitrites, and some nitrates (I have done a PWC since testing, so not sure exactly what they're at now, but was around 20ppm before the change)

My tap water has 0 for ammonia, nitrites, and nitrates.
  • #5
I think your bio load at start may have been to high, and may have caused the cycle to stall at some point. First for the fish make sure you are using water conditioner like Prime to bind ammonia into a non toxic state, this will offer your fish some protection. I had a similar problem with my 38G, took all over 2 months to cycle, and what I feel helped my situation was adding an air pump to improve oxygen levels in the water. It’s a deeper tank so I felt maybe the surface agitation from the filter wasn’t enough and within a couple of days of adding the pump I started to see nitrate. May have been dumb luck, but I figured options can’t hurt.

Another option maybe using some form of bacteria in a bottle. I did this on my brother 20G which wasn’t cycling and overstocked. We got a bottle of One and Only believe it was for up to 30G. Did a huge water change at least 50-60%, refilled added prime and then dumped the whole bottle of bacteria in. Next day we had some1ppm ammonia 1ppm nitrite and about 5ppm nitrate. Waited one more day did a 25% water change, tested again the next day 0 ammonia 2ppm nitrite, nitrate was present but really low. Next day after that 0 ammonia and nitrite 5ppm nitrate. One more water change and haven’t looked back since. Since that experience I started a 75G with One and Only and was cycled in a week, however that was fishless and using pure ammonia. Hopefully some of this get you going in the right direction and Good Luck.
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  • #6
I'm trying to stay away from bacteria in a bottle, I'd rather have it cycle by itself so I'm not reliant on a product to prevent a crash.

The only thing I can think of at this point is that when I do the water changes, the chlorine from my tap water kills off the bacteria before the conditioner has a chance to work.

As I don't have a 13 gallon bucket to condition the water in beforehand, I am going to try doing daily 3 gallon water changes instead of weekly 25% water changes.

Hopefully this will work.

Also, just as a matter of interest, there has always been a bubbler at the bottom of the tank, so I doubt that is the issue.
  • #7
In the long run buying a bigger container to hold water overnight now is gonna be way better than having to change water every single day imo
  • Thread Starter
  • #8
Agreed, but for now I already have a 3 gallon fish water bucket
  • #9
Higher pH levels= more ammonia. Try to lower your pH your ph level should be around 6.8 to 7.8. Or get an ammonia remover.
  • #10
Higher pH levels= more ammonia. Try to lower your pH your ph level should be around 6.8 to 7.8. Or get an ammonia remover.
Not really, but I sorta know what you're trying to say. While a higher pH does increase the toxicity of ammonia, it's only to a point. Anything above 6.5 will still have ammonia and the difference between ammonium levels at 7.8 vs 8 would be little-none.

Ammonia gains a hydrogen ion in low pH, turning it into ammonium (NH4). This is a bad thing when cycling a tank. Since AOB can not nitrify ammonium, the tank will never cycle.
Inactive User
  • #11
What am I doing wrong?

I don't think you're doing anything in particular that's wrong. The fundamental issue is that there are in excess of 20 factors that can affect nitrification in aquariums (Chen, Ling and Blancheton, 2006).

Many of these factors can't be accounted for by hobbyists (complexity of kinetics, expense of testing equipment, etc.) and so we can only speculate as to why some tanks seemingly don't cycle even when using established filter media.

My interpretation of many threads like this is that it's related to excess organics (solid fish waste, excess fish food). Nitrifying microorganisms (i.e. our "beneficial bacteria") compete for space and oxygen with other bacteria, notably heterotrophic bacteria that utilises organics as a metabolic substrate. When organics are in excess - such as with a high initial bioload in fish-in cycling or when using too much fish food in fishless cycling - our "beneficial bacteria" are outcompeted.

This phenomenon is fairly well accounted for in aquaculture biofiltration design: Chen, Ling and Blancheton (2006) provides an excellent summary of the scholarly literature in that regard. The causal relationship between excess organics and poor biofiltration would, in my mind, also apply to household/retail aquariums, but I haven't noted any literature that specifically examines it so it's rather speculative.

In any case, my recommended solution would just be to feed less, to vacuum the substrate more aggressively, and to do larger and more regular (50% every other day) water changes. I have, in the past, also recommended scrubbing out the exterior of the filter in order to remove accumulated heterotrophic bacteria in order to make room for nitrifying microorganisms.

I'm trying to stay away from bacteria in a bottle, I'd rather have it cycle by itself so I'm not reliant on a product to prevent a crash.

There is, I feel, a qualitative difference between the various bottled bacteria products. For example, most retail products (Seachem Stability as an example) have almost no rigorous evidence basis as to its effectiveness, which is not to say they don't work or can't work, but the evidence is neither present nor rigorous.

Compare that to Dr Tim's One and Only (and Tetra SafeStart which is a derivation product) to which Timothy A. Hovanec ("Dr Tim") contributed to its development. Timothy Hovanec is a noted microbiologist and authority on nitrification: he is among the very few scientists that has published scholarly studies on nitrification in aquariums in peer-reviewed, scientific journals. In that regard, I would not hesitate in recommending either product.
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  • #12
Referencing peer reviewed literature? You trying to make me fall in love?

Thank you, I will take your advice into consideration.
  • Thread Starter
  • #13
Ok, just an update on the tank.

55 gallon is still showing no nitrites or nitrates, and with the daily bucket change of water (3 gallons) the ammonia has come down to 0.5 ppm.

I have still been swapping filter media between the established 10 gallon and the 55 gallon, once every few days.

The 55 gallon is now growing algae - could the algae be eating the nitrates and leaving me with a 0 reading, and the bacteria in the filter just can't keep up with whatever is producing ammonia?

As for ammonia sources, aside from the fish themselves (which should be a fairly low load for a tank this size), we do not overfeed (we err on the side of under-feeding).

There may be a kuhlI loach corpse or two...there were originally 5, two of which made their way into the filter and died...and we haven't seen the other three since putting them in (we do have a fry guard on the filter now, just for them).

I understand this could be normal for them, but if they're dead, could it be that they are the source of the ammonia, and so my readings are normal for an established tank, I just need to go on a dead loach hunt?
  • #14
Yep definitely need to locate them and remove if they have died. I know it’s hard to be patient also the fish can go a few days without eating so I would recommend feed sparingly every four days till that ammonia drops. Also if using the apI freshwater master kit. Be sure to shake the nitrate bottle 2. I mean really shake it the reagents in that bottle are known to crystallize. Since you have a tank that’s up and running definitely test Nitrates there and see if you get a positive reading just to rule out faulty test equipment
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  • #15
Yeah, I test that tank about once a week, and have seen nitrates in it.

Gonna be a pain searching for loaches...
  • #16
I don’t envy that job. Best of luck with the search.
  • Thread Starter
  • #17
50% water change today, ammonia down to 0.25 ppm. A thorough search of the gravel revealed one kuhlI still alive, no bodies. Found what are probably kuhlI remains in my filter sponge, so I thoroughly cleaned the sponge out (in aquarium water). Upon reflection the holes in the sponge are probably big enough for them to squeeze into, so all the dead ones are probably there. So I will be getting a new sponge, just in case. I know that might stall the cycle, but better a stalled cycle than fish remains in the filter.
  • #18
Sorry to hear that! As unpalatable as it may sound; If that sponge has been in there a few weeks you may just want to keep it in there
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  • #19
Hopefully this will be the last update, but we dosed the tank with Dr. Tim's One and Only yesterday and have already seen a decrease in ammonia, with nitrates on the rise. I realize that the nitrate reading could just be residual nitrates that were in the bottle of Dr Tim's, but since ammonia is also dropping, I am hopeful that this means it worked as it should.

Thank you all for your help!
  • #20
Fingers crossed

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