Does this seem normal in Fishless cycle?

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fishtonic1

Aquarium Advice Apprentice
Joined
Jul 30, 2024
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melbourne
Hello all. I am currently doing my first fishless cycle in 13.5g / 50L tank. Have been doing so for nearly a month.
My tank is planted, although the Pennywort and Wisterias are deteriorating quite a bit...
Since i first dosed ammonia and been adding bacteria daily, here are my parameters:

Ammonia: ~1-2 ppm
Nitrite: 0 ppm
Nitrate: 0 ppm
PH: 6.0

Does this seem right? I feel like Nitrites should have appeared by now
 
Your low pH suggests a low carbonate hardness (KH). At a low enough KH the nitrogen cycle can't function.

We need to do a bit of investigation. You need to get the KH of your aquarium water and tap water.

If it's low (or zero) you have 2 options.

  • Add carbonates/ bicarbonates to raise the KH. This will also raise the pH.
  • Forget about cycling the tank. Keep fish that prefer really low pH. Although the KH will inhibit the nitrogen cycle, at such a low pH any ammonia is going to be in the form of non toxic ammonium and completely harmless to fish.
 
Just to add a bit of info on the "forget about cycling the tank" bit.

Your ammonia test is actually testing for Total Ammonia Nitrogen (TAN). This is a combination of free ammonia and ammonium. It's only the free ammonia that is toxic to fish.

The proportion of free ammonia and ammonium is temperature and pH dependant. As these 2 parameters rise, more of the TAN is free ammonia and less of it is ammonium. The reverse happens as these 2 parameters fall. Free ammonia turns into non toxic ammonium. At pH below 7 you can pretty much say that all the TAN in your test is ammonium. You can certainly say that if your pH is as low as 6.

This is a thread on ammonia toxicity if you want to learn a bit more.


So, while it may not be possible to cycle an aquarium with very low KH, because low KH will be reflected in a low pH it doesn't matter too much if you arent cycled. What you would have to watch out for is if pH rises without you knowing. As you wouldn't be cycled ammonia will build up. At low pH this is going to be non toxic ammonium, but if the pH rises then ammonium will become toxic free ammonia.

Not all fish are going to appreciate such a low pH/ low KH environment. So if you go down this route select your fish species carefully and have a good acclimating process as any fish you buy may not have been bred in such acidic conditions.

The other side of this is, if you decide to artificially raise the KH and pH, you need to keep on top of that. There are salts you can buy, that raise KH or you can have calcium carbonate features in your aquascape to raise the KH, but monitor things because if the KH gets depleted for any reason, then your cycle would cease to function.

This might also be a factor in your poor plant growth. Aquarium plants tend to do better in water with some KH in it.
 
To add to Aiken's post, you are probably going to have took for wild caught fish to get ones that prefer that low pH. The fish that when wild liked it but have become farm raised are usually raised in a much higher pH and harder water than their wild ancestors. Unfortunately, if you look up fish species on the internet, the information applies to wild specimens without taking into consideration that what is mostly available in fish stores are farm bred fish. Trying to convert them back to the wild parameters usually does not end well. Just an FYI. (y)
 
Your low pH suggests a low carbonate hardness (KH). At a low enough KH the nitrogen cycle can't function.

We need to do a bit of investigation. You need to get the KH of your aquarium water and tap water.

If it's low (or zero) you have 2 options.

  • Add carbonates/ bicarbonates to raise the KH. This will also raise the pH.
  • Forget about cycling the tank. Keep fish that prefer really low pH. Although the KH will inhibit the nitrogen cycle, at such a low pH any ammonia is going to be in the form of non toxic ammonium and completely harmless to fish.
I tested my tank and tap water, here are the results:

Tank:
GH: 60 ppm
KH: 0 ppm
PH: ~6
Nitrite: 0 ppm
Nitrate: 10 ppm

Tap:
GH: 0 ppm
KH: 0 ppm
PH: 6.5
Nitrite: 0 ppm
Nitrate: 0 ppm
 
OK. Essentially you can't cycle a tank with zero KH. If you want to raise KH you can do the following.
  • A bag of crushed coral in the filtration or mix some crushed coral into your substrate. This will slowly disolve and add both GH and KH.
  • Cuttlefish bone is calcium carbonate same as coral. Putting a piece of cuttlefish bone in your filtration or somewhere in your aquascape will also disolve raising both GH and KH.
  • Mix baking soda in your water. This is sodium bicarbonate and will raise KH bit not GH. Add it slowly, let it fully disolve and check the KH and add more until you get to your desired KH.
  • Mix an aquarium specific buffer salt. Seachem Alkaline Buffer will raise KH. Seachem Equilibrium will raise GH and also have some other minerals that are good for plants. Seachem Replenish will also raise GH but isn't suited to planted aquariums.
 
OK. Essentially you can't cycle a tank with zero KH. If you want to raise KH you can do the following.
  • A bag of crushed coral in the filtration or mix some crushed coral into your substrate. This will slowly disolve and add both GH and KH.
  • Cuttlefish bone is calcium carbonate same as coral. Putting a piece of cuttlefish bone in your filtration or somewhere in your aquascape will also disolve raising both GH and KH.
  • Mix baking soda in your water. This is sodium bicarbonate and will raise KH bit not GH. Add it slowly, let it fully disolve and check the KH and add more until you get to your desired KH.
  • Mix an aquarium specific buffer salt. Seachem Alkaline Buffer will raise KH. Seachem Equilibrium will raise GH and also have some other minerals that are good for plants. Seachem Replenish will also raise GH but isn't suited to planted aquariums.
I see. Does it matter if i have i higher KH and lower GH?
Also, which one of these methods would you reccommendd? I was thinking baking soda as it's quite simple but I'm concerned about the GH levels. And I assume I'd have to add more baking soda when I do water changes and that.
 
It really depends on what fish you want to keep. With GH of 60ppm you are "soft" water. If you plan on keeping fish that prefer soft water you don't need to adjust your GH much, if at all. Going the coral/ cuttlefish bone route would probably be good for adding a little KH and GH and you could do this and leave it until it all disolves.

If you wanted to keep fish that prefers harder water I'd do with the buffer salts as you could raise it whatever you wanted just by adjusting the amount of salt you add.

Baking soda wouldn't be my preferred route because sodium isn't great for freshwater fish, but if you are only wanting to bring KH up a little it should be fine. If you have baking soda in the cupboard, then it's fine to add some to get your cycle started and decide on a permanent solution later. Add a teaspoon for every 10 gallons of water and see what that gets KH to.

I'd have a think about what fish you want to keep.
 
I
It really depends on what fish you want to keep. With GH of 60ppm you are "soft" water. If you plan on keeping fish that prefer soft water you don't need to adjust your GH much, if at all. Going the coral/ cuttlefish bone route would probably be good for adding a little KH and GH and you could do this and leave it until it all disolves.

If you wanted to keep fish that prefers harder water I'd do with the buffer salts as you could raise it whatever you wanted just by adjusting the amount of salt you add.

Baking soda wouldn't be my preferred route because sodium isn't great for freshwater fish, but if you are only wanting to bring KH up a little it should be fine. If you have baking soda in the cupboard, then it's fine to add some to get your cycle started and decide on a permanent solution later. Add a teaspoon for every 10 gallons of water and see what that gets KH to.

I'd have a think about what fish you want to keep.
I was thinking guppies, gourami, corys
 
At a pH of 6.0, nitrification is going to happen very, very, very slowly even with the higher KH. Nitrification stops at a pH under 6.0 ( or 5.0 according to some studies) so with our limited test kits, you could be under 6.0 just enough to stop the cycling process. Optimal pH for nitrification is 7.3-8.0.
Unless you are getting wild caught cory cats, your water is not ideal for the tank bred ones as they are mostly bred in 7.0-8.0 pH water to accommodate aquarists around the world. They also like current in their tank ( as do the guppies) which the gouramis generally prefer slower moving water so your combination is not really an ideal combination.
With all that said, with a pH of 6.5 in your tap water, any ammonia produced in the tank by the fish will naturally be converted to non toxic ammonium so nitrification is not really necessary and can be controlled in volume by doing routine water changes. I surmise your pH is dropping because you are adding something to the tank that is an acid. ( ammonia is an acid). You may want to reconsider the fish you want so that their demands better match your water's parameters. "Chasing" parameters has a bad habit of not being economical or beneficial to the fish. You have ideal water for wild caught soft water fish from S. America and Asia and some fish from Asian farms.
Hope this helps (y)
 
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