Cycle stalls

[Ktrk]

Hi all,

I have a fishless cycle question (I know it's a topic that is covered to death but there's so many elements).

I have had the tank for a year and been trying to complete a fishless cycle in it ever since.
It seems to get to the same point every time: ammonia, then around a week or so later nitrite spike, then disappears again and nitrate starts to increase so I do water change and keep amm. topped up to 2ppm.

The problem is the last bit never seems to complete - the amm. never completely dissappears within 24 hour. Always takes 48...
Nitrite remain zero after initial spike, and nitrate continue to increase until I water change at around 80ppm.

This the 4th time now, as it gets stuck at this point for weeks, then I lose interest, come back to it a couple months later and we start again.

It is planted, anubias on wood, crypt and rotala in substrate, but that shouldn't be stopping the amm. conversion should it?

Any help appreciated as im losing the will to live and i really dont want to as ive loved getting in to this hobby.
Thank you!

 

[Aiken Drum]

How long have you been giving it each time you have tried to get the tank cycled?

Do you have a suitably sized filter for your tank?

How are you dechlorinating your water when you do these water changes?

Do you know if you have hard or soft water? In particular carbonate hardness?

What temperature is the tank water at?

Is there a reason for the fishless cycle?

We get a lot of traffic on the forum with people having trouble cycling a tank. By far more people have trouble with fishless cycles than fish in cycles. They dont really understand the process, dont understand how long it takes etc. Almost without fail switching to a fish in cycle solves the issue.

After a year and several aborted attempts at fishless cycles i would be looking at a different route and getting some fish swimming around in a tank.

 

[Ktrk]

I know, ive done it fine before which is why im stumped this time. The only difference is this one has live plants.
I know it takes weeks to months, this current stalled cycle is at 12 weeks now (this time around)
I have another tank that I have successfully cycled before which has been happily going for 2 years.

Temp is 82, dechlorinated with aqua safe by Tetra, soft water, filter size is fine for the tank.
Went for fishless cycle for fish husbandry really. It can stress them doing a fish in cycle and so thought if I could avoid it the better..
It's a 7 gallon that will ultimately be housing a betta.. ��

 

[Aiken Drum]

Carbonate hardness (KH) is used up by the nitrogen cycle, once it gets low your cycle can slow down, once its gone it will cease to work at all. Enquire of your water company what your KH is. This can usually be done online.

Live plants will take up some ammonia and can slow down the growth of denitrifying bacteria. But the other side of the equation is because some ammonia is being consumed by plants you dont need as much denitrifying bacteria, so swings and roundabouts IMO.

If done properly a fish in cycle should be stress free and harmless. What used to happen is put fish in a tank, when they died you replaced them. When they stopped dying you are cycled. This is where the bad reputation for fish in cycles come from. A lot more is understood about ammonia and nitrite toxicity than used to be the case. Testing has improved. This all leads to it being much safer to do a fish in cycle than was historically the case.

 

[Aiken Drum]

A good way to speed up this process would be to put a small amount of filter media from an established filter into your filter, or get a sponge from an established filter and squeeze it into your tank water. This will seed your filter with the bacteria you are trying to grow and speed up the process. You say you have a cycled tank.

 

[Ktrk]

Thankyou for your help! I'll have a look at kh! Is there anything that i could look at changing if kh is the problem?

Also, do you think a betta would be hardy enough for fish in cycle?

 

[Aiken Drum]

Under normal circumstances KH is replenished through a water change. A fishless cycle doses far more ammonia than fish in a tank will produce, so if KH is low from your tap a fishless cycle will use it up more quickly than a stocked tank would. This is why a water change often restarts up a stalled cycle.

Cuttlesfish bone in your tank or filter, or a bag of crushed coral in the filter will replenish KH if water changes isnt sufficient.

If you are doing a fish in cycle properly water parameters wont get close to hazardous. A betta in 7g should be perfectly fine "if" you do it properly.

 

[Ktrk]

It's just a standard sponger filter so I'm not sure how I'd add any coral etc but I'll have a think.

Thanks again, I might look at adding the betta then and seeing how it goes.
What would you say is doing it properly, daily water changes to compensate ammonia? Or adding amm. binder?

 

[Aiken Drum]

To cycle a tank you need to grow denitrifying bacteria to consume ammonia and nitrite that your tank produces. The bacteria needs an ammonia source to grow colonies sufficient in size to consume all the ammonia and resultant nitrite and turn it into nitrate which typically you remove through your regular water changes.

A fish in cycle uses fish waste as an ammonia source and regular water changes are undertaken to ensure that water parameters are maintained at relatively non toxic levels.

Set up your tank. Make sure everything is running smoothly. Make sure you have used a water conditioner product with any tap water you have put in your tank. Seachem Prime is a water conditioner that will also detoxify some ammonia for a day or two, so is a good choice for a water conditioner while cycling a tank with fish.

You should have a test kit. Preferably a liquid test kit. It should test for ammonia, nitrite, and nitrate.

In ideal circumstances you should be starting a fishless cycle with a low bioload (number of fish). 1 small fish per 10 gallons/40 litres is a good number of fish, but this can be tweaked a little for fish that are social and don’t do well on their own. Ideally a hardy type of fish. You may have fully stocked (or overstocked) your tank before you knew about cycling. In these circumstances, if its not possible to return fish, you will have to make the best of it.

If you haven’t already done so, add your fish. Acclimate them to the water in your tank before doing so.

Feed lightly to start with. Daily as much as is eaten in 2 minutes, or as much as is eaten in 3 minutes every 2 days. You can increase to full feedings if you are confident your parameters aren’t getting too elevated too quickly and water changes don’t become a daily thing.

Start to regularly test the water for ammonia and nitrite. At least daily. Depending on your bioload you could start to see ammonia quite quickly. Nitrite will likely take a little longer to appear.

Your target should be to keep ammonia + nitrite combined no higher than 0.5ppm by changing water whenever your water parameters exceed this target. 0.5ppm combined is a level of waste that is sufficient for your cycle to establish but relatively safe for your fish.

If you see 0.5ppm ammonia and 0.0ppm nitrite (0.5ppm combined) then leave things be. If you see 0.5ppm ammonia and 0.25ppm nitrite (0.75ppm combined) then change 1/3 of the water. If you see 0.25ppm ammonia and 0.75ppm nitrite (1.0ppm combined) then change 1/2 the water. If water parameters get worse than these levels it may require multiple daily 50% water changes to maintain safe water conditions. This is more likely to happen with a fully stocked tank.

Remember to add water conditioner whenever you put tap water in the tank.

Over time the frequency of water changes and amount you need to change to maintain your ammonia + nitrite combined target will reduce. You can also start testing for nitrate and should see this rising. If you are finding the ammonia and nitrite in your tests are consistently low, and you aren’t already fully stocked, you can add a few more fish. It may take a few weeks to get to this point.

Once you add a few more fish, continue to regularly test the water and continue to change water if you exceed the 0.5ppm combined ammonia + nitrite target. With added bioload the frequency of water changes and amount you need to change may increase again until your cycle has caught up. Again once you are consistently seeing low ammonia and nitrite you can add some more fish. Rinse and repeat with testing, water changes, and adding fish when safe to do so until you are fully stocked.

You can then cut back on water changes to control nitrate only. Typically you want to keep nitrate no higher than 40ppm, but I would recommend changing some water every 2 weeks even if your water test says you don’t need to.

A fish in cycle from an empty tank to fully stocked can take several months.

A good way to speed up this process would be to put a small amount of filter media from an established filter into your filter, or get a sponge from an established filter and squeeze it into your tank water. Perhaps you have a friend who keeps fish who could let you have some? This will seed your filter with the bacteria you are trying to grow and speed up the process.

Another option is bottled bacteria like Dr Tims One + Only or Tetra Safestart. These products wont instantly cycle a tank as they claim but in a similar manner to adding established filter media they can seed your filter with the bacteria you are trying to grow to establish your cycle. These products are hit and miss as to whether they work at all, but are an option if established filter media isnt obtainable and may speed up the process from several months to several weeks.

 

[Ktrk]

Thankyou.
Ive got the API master kit so I'm good on that front.

It'll only have the betta in it, maybe a snail depending on how feisty the betta seems to be, so the bioload should be small.
I'll give it a go and keep testing daily!

The other thing I have noticed is that my ph straight from the tap is the high 6, almost 7. As the cycle goes on the pH drops lower as a by-product of the bacteria it seems. I've read that can cause a cycle to stall as well, but other than adding chemicals (ph up) I'm not sure how to fight that, as with every water change, and also as a direct result of the bacteria growing and doing its thing, it becomes more acidic again

 

[Aiken Drum]

This looks like a symptom of low KH.

Its not low pH that stalls cycles, but low KH and a sign of low KH is pH dropping.

KH absorbs any acid that goes into the water. When KH runs out your water loses the ability to buffer acid and so any acid will cause pH to crash. A lot of the natural processes that go on in your tank acidify the water. Nitrate from the nitrogen cycle is acidic. CO2 from fish respiration is acidic. With little or no KH these processes will cause your pH to drop.

How much is your pH dropping?

Looks like its quite important we look into what your KH is. Most water companies have this information online. Make sure you get the units KH is measured in. Different reports will use different units, usually measured in ppm or dKH.

As previously said, KH will get used up more quickly when doing a fishless cycle than it will when you have fish in a tank, so it may not be so big of a deal going forward and you may be able to manage it through water changes. I wouldnt go trying to chemically alter pH, it usually causes more issues than it solves.