Tank Cycling, Water Changes And Effect On Ammonia/nitrite/nitrate

[alanbur]

I have a small tank - about 15L - yes, I know that's tiny but that's all I have space for. The tank previously had goldfish in it, but after they died (eek!) the tank was left fallow with the pump turned off for about 6 months and was a green soup of algae. I rescued the plants and filter media but I figured the gravel would have been anerobic for some time, so I took it out sterilized it. I put everything back in the tank, filled it up and left it running for a week before introducing three Neon Tetras into it on Saturday. After some research I now realise I should have cycled the tank *first* - duh!, so I've got a test kit and tested the water over the last 2 days - day 3 & 4 after the fish were introduced. I've also added some Tetra SafeStart yesterday. The readings over the last 2 days have been:

pH 6.8 6.6
NH3 0.0 0.0
NO2- 0.5 0.5
NO3- 5.0 0.0

Although the fish seem perfectly happy, the N02- is a little high so I've done a 25% water change, left the tank for a couple of hours & retested, and the NO2- is unchanged - with a 25% change I'd have expected *some* sort of drop. Any ideas as to why the NO2- hasn't budged? is this normal? Does the SafeStart contain a source of NO2- to keep the bacteria it contains happy?

Also when I tested I was expecting to see at least *some* NH3 but it is zero. I'm assuming (hoping!) that this is because I reused the filter media & plants from the old tank and the tank is quite heavily planted (considering its size). Or is it possible that the NH3 spike is still to come?

I'm determined not to lose any of these fish if I can possibly help it, so I'd be grateful for any suggestions or comments, thanks!

 

[alanbur]

One more 25% water change and now the NO2- is down to 0.25ppm, which I figure is bearable. pH & NH3 are unchanged - I'll retest tomorrow morning.

The Neon Tetras are *so* much nicer than the goldfish that were in the tank before, I'd hate to lose any. The filter is an in-tank one and it is set with the outlet pointing along the back of the tank. One of the Neons has taken to 'surfing' in the flow every now and then - swimming along just below the current, then up into it & shooting backwards along the tank, out of the current then back up for another go. It does it 2-3 times before mooching off amongst the plants & rocks.

 

[fatheadminnow]

What kind of test kit do you have?

Your plants are probably utilizing all of the Ammonia that your fish put out, giving you a zero reading for Ammonia.

Also, Neon Tetras should not be in new tank that has not been running for at least 6+ months, let alone a fish-in cycle.

So do not be surprised or shocked if some of your fish die.

-FHM

 

[waterdrop]

You're doing great! You've got the right idea! You're just too timid. ANY time you see a test result the likes of 0.50ppm or higher its time for bolder action. That level of either nitrite(NO2) or ammonia will be much more deadly to them than the effect of a larger water change. Just be sure to condition the new tap water and roughly temperature match with your hand.

Don't worry, even with zero ammonia reading, the bacteria are being fed and the fish-in cycle will be progressing. You can read about fish-in cycling here in our forum. Your goal is to figure out a percentage and frequency of water changes that will keep you always below 0.25ppm when you come back to test and can do another water change.

The stuff FHM said is true, neons/cards are ideally introduced after a tank is 4 to 6 months beyond fishless cycling but don't worry about it. You're already into this and you sound like you really like your new friends and will do the needed water changes for them for the month or so it will take. Besides, the tank is small, which is good.

~~waterdrop~~

 

[alanbur]

fatheadminnow:
The test kit is a API Freshwater Master Test Kit. Thanks for the tip about the plants, I knew they could use the Nitrate, but I didn't know they could use the Ammonia. I assume they can't utilise the Nitrite until it has been converted to Nitrate? I did notice that the old plants have greened up remarkably since the fish went in, so that explains it. After reading various articles on tank cycling I know the Tetras shouldn't be in there, but too late now to do anything about it - however I'm determined to give them the best chance I can.

waterdrop:
Thanks for the tip about being more aggressive with the water changes. I've been religiously conditioning & temp matching the water, so at least I got that bit right. I've just retested and the Nitrite has crept back up to between 0.25 & 0.5, so I've done a 30% water change and it is back down to 0.25. And yes, I guess having a small tank is good in terms of making water changes easy, but I'm aware that it will be much more prone to fluctuations than a big one, and that I'm going to be have to be diligent in monitoring it.

I thought that once the tank cycling was complete you could just add whatever fish you were stocking with? What changes happen in the 4-6 months after cycling that make the tank more suitable for Neons?

My intention is to eventually stock it with 4 Neons and 4 Glowlights which I figure is about as much as the tank (15L) will bear, does that sound about right?

 

[alanbur]

Ammonia still 0, Nitrite down to about 0.125 (1/2 way between colours), nitrate around 2-3. Done another 25% water change, but it's looking hopeful so far.

 

[fatheadminnow]

Ammonia still 0, Nitrite down to about 0.125 (1/2 way between colours), nitrate around 2-3. Done another 25% water change, but it's looking hopeful so far.

Looks like you are doing well!

Keep up the good work!

-FHM

 

[alanbur]

Thanks! I'm surprised the Nitrite has stayed down, I'm wondering if the Tetra SafeStart is helping any - I've read mixed reports on its effectiveness. I figured it couldn't hurt, and as I was stuck with doing a cycle with fish it was probably worth a try - with such a small tank I only needed the smallest bottle, so it didn't break the bank - unlike the master test kit!

Can you get refills for the kits, or do you just have to buy a new one?

 

[fatheadminnow]

Thanks! I'm surprised the Nitrite has stayed down, I'm wondering if the Tetra SafeStart is helping any - I've read mixed reports on its effectiveness. I figured it couldn't hurt, and as I was stuck with doing a cycle with fish it was probably worth a try - with such a small tank I only needed the smallest bottle, so it didn't break the bank - unlike the master test kit!

Can you get refills for the kits, or do you just have to buy a new one?

With a fish-in cycle, we never really see a spike in Ammonia and/or NitrIte.

More or less, we just see its presence for a couple of weeks, and then it is gone. Then we start to see our NitrAte go up.

For the API Test Kit, you can just buy individual test kits for like Ammonia, NitrIte, NitrAte and pH if you run out of one.

That way if you run out of one you don't need to buy the entire kit again.

-FHM

 

[alanbur]

Ah, that explains it, thanks - most of the info I've read relates to fishless cycling. And good to know that you can get replacements for the kits - having used one I feel much more confident that I can 'manage' the tank and I'll be using it regularly.

 

[waterdrop]

I thought that once the tank cycling was complete you could just add whatever fish you were stocking with? What changes happen in the 4-6 months after cycling that make the tank more suitable for Neons?

Nobody knows, its just an observation that keeps getting repeated over and over.

~~waterdrop~~

 

[alanbur]

Nobody knows, its just an observation that keeps getting repeated over and over.

Hmp, sounds like cargo cult science to me...

 

[nickelplates]

Nobody knows, its just an observation that keeps getting repeated over and over.

Hmp, sounds like cargo cult science to me...

And like the best cults there are many theories . One big effect is that over time you accumulate a wide variety of organisms living in the biofilm which is a living slimy film produced by bacteria that covers all the wet surfaces in your tank it is home to nitrifying bacteria, algae, protozoa, and microscopic invertebrates. It takes longer for a real diversity of organisms to build up than it does to cycle your tank, it is well known that this film is important to fish like otto's which feed on it although it's relationship to neon tetras is less obvious. Of course for practical reasons you clean most of this off the 'viewable' glass of your tank but you actually should not remove it from the other surfaces.

A less interestingly but more pragmatic theory is that sensitive fish don't like being in a tank the fishkeeper is still learning how to look after rather than one where he (and therefore the water chemistry) has settled into a steady routine.

Whatever the reason as Waterdrop says it has been observed over and over that certain fish do badly in newly cycled tanks.

 

[alanbur]

And like the best cults there are many theories . One big effect is that over time you accumulate a wide variety of organisms living in the biofilm which is a living slimy film produced by bacteria that covers all the wet surfaces in your tank it is home to nitrifying bacteria, algae, protozoa, and microscopic invertebrates. It takes longer for a real diversity of organisms to build up than it does to cycle your tank, it is well known that this film is important to fish like otto's which feed on it although it's relationship to neon tetras is less obvious. Of course for practical reasons you clean most of this off the 'viewable' glass of your tank but you actually should not remove it from the other surfaces.

That makes sense, although I suppose for fish that don't feed on it the only possible link is the effect of the microfauna on the water quality. I think there's an interesting research project in there for some PhD student to track the changes over the first 6 months and find out what is really happening - the tank cycling process seems to be pretty well understood, but what happens after that seems to be more of a mystery. And I'm sure the findings would have applicability to commercial fish rearing as well.

And thanks for the hint about cleaning the other surfaces - I have a nice chunk of granite in the tank that in the past I've aggressively cleaned when it got grotty, it's clear from what you say that I should leave it alone to provide a home for the inhabitants of the tank that I *can't* see.

A less interestingly but more pragmatic theory is that sensitive fish don't like being in a tank the fishkeeper is still learning how to look after rather than one where he (and therefore the water chemistry) has settled into a steady routine.

Now that's a theory I *can* believe - I'll put my hand up to being inexperienced

Thanks, this forum is an invaluable resource for neophytes, the thing I've found most helpful is that the people here can *explain* why you need to do certain things, rather than just "Do this, no we can't explain why".

 

[alanbur]

Latest sets of readings:

pH = 6.5
NH3 = 0.0
NO2- = 0.0
NO3- = 2.5

I've tested it three times because I didn't believe the readings - can my tank *really* have cycled in less than a week? I added another dose of Tetra SafeStart last night, in proportion to the water changes I've done over the last 2 days, perhaps is really *does* work? Puzzling...

The pH seems a little low at 6.5, is that something I need to do anything about? I live in a soft water area, so although the tap water is about 7 I'm not surprised it dropped. I also noticed a dip the last time I added the SafeStart, so it may be that.

I think I'll watch it for a couple of days before adding any fish though, I was planning on adding 4 x Glowlight Tetras + 1 Neon Tetra to being the total Neons to 4, as I know they like to be in groups - 5 or 6 would be better, but I don't want to overload my tank.