Unexpected Nitrate Readings

[nitrochicken]

I've had fish in my tank for a week now. Fishless cycle took approx 6 weeks. I now have 7 Galaxy rasboras, 2 endlers, 3 cherry shrimp and 2 snails in a 29L aqua-one.

Before I got the fish last week, I did an 80% water change, tested the water and the nitrate readings were about 20ppm.
Throughout the week, I have been testing every couple of days just for ammonia and nitrite, to make sure my fish were safe and they have stayed at zero

The strage thing is that when I tested tonight, nitrite/amm are both zero still but nitrate has dropped to 5ppm.
I thought nitrate was supposed to go up not down??? And I thought this is what we control by changing the water.
This seems wierd to me. I do have 4 plants and I know they can use up nitrate but I wouldn't have thought this much?

With this in mind, how often should I be changing the water and how much? Or should I wait for nitrate to go up first(if it even does?)

Thanks

Dale

 

[ox5477]

Your plants could used this nitrate... I'm not sure how fast they use it either, but that could be one explination. Another might be your test kit.

How old is the kit and what brand is it? Liquid test or strips?

 

[nitrochicken]

Its a nutrafin liquid test kit and I've only had it about 7 weeks, since I started fishless cycling. It has been reliable so far.

 

[ox5477]

It still should be as well. If it was a year or more older, then you could start doubting it. I would say its prob your plants then cause I cant think of what else it could be, plus your water volume is pretty small so 20ppm in that small volume isnt alot. How big are the plants? If you have a pic of the tank, that would be best

Ox

 

[nitrochicken]

Here is a picture if the tank taken last week, there is a lot less algae now on everything so I think the shrimps/snails have been doing their job

Dale

 

[rabbut]

With low readings of nitrate, most kits are innacurate. Take nitrate kit results as a guide, not as a true value

Those plants would have used some nitrate but not a lot. That said, the fish you have equate to quite a low bio-load, so it is possibly where it's gone...

We don't just waterchange to remove nitrate. Other things build-up over time, such as orgainics in the water, and others depleate, such as KH. Waterchanges are important because they keep things stable. Nitrate indicates if your maintanance is enough assuming you are heavily stocked or don't have any plants. Plants or light stocking tend to distort the bigger picture given by a nitrate test

20% weekly is what I'd recomend, or if you are busy one week, 30% every other week would be OK. Little and often is better than not doing any untill the tank crashes and you can't keep fish alive untill you have done a month of daily 10%'s to fix the lack of maintanance

All the best
Rabbut

 

[nitrochicken]

I had a look through previous posts on the same subject and some of them suggest that the plants will also use up ammonia. Is this correct? Wont my bacteria die off if this is the case, from starvation?

Thanks

 

[rabbut]

In part yes, they use it in preferance to nitrite, which they use in preference to nitrate, and this can lead to issues if you do too much prooning. Miss Wiggles tank mini-cycles after large prooning sessions apparently, so little and often is the way to go to avoid issues

HTH
Rabbut

 

[waterdrop]

Interesting, I guess the plants would be the only thing to explain it.

Is the tank really 29L/7.7G or was that a typo and its a 29G? It looks a bit like it could be a 29 gallon.

But the nitrate thing would make more sense if its a small tank. Just looking at it, it does not appear to be the type of heavily planted tank that would take up a lot of amm/nitrite/nitrates but the plants do appear to be healthy, so they may have just the right conditions to be growing and absorbing. Obviously there is sufficient light, given the algae. Are you adding any liquid and/or substrate supplements for the plants?

Another option from a different angle would be to pick up a nitrate test kit from a different manufacturer and try testing with that, following directions carefully, as nitrate tests are notoriously tricky and dependent on all the details.

I agree about maintaining good maintenance and about keeping the plant pruning to a minimum, when its done (frequent small amounts of pruning too, when/if the plants get to that point.)

~~waterdrop~~

 

[backtotropical]

In part yes, they use it in preferance to nitrite, which they use in preference to nitrate

Aquarium plants don't use nitrite, only ammonia and nitrate. I'm not sure why, but that is the case.

 

[waterdrop]

In part yes, they use it in preferance to nitrite, which they use in preference to nitrate

Aquarium plants don't use nitrite, only ammonia and nitrate. I'm not sure why, but that is the case.

Yes, I was going to bring that up with rabbut as that's what I've always heard too, that its only ammonia and nitrates they sometimes use. I also seem to remember that it varies quite a bit by plant species and the environmental situation of the plant - does that sound right to you too BTT?

~~waterdrop~~

 

[OldMan47]

The nitrate test kits that advise you to mix ingredients for at least 30 seconds work better and are more accurate if you double the time. You can think of the 30 seconds as the bare minimum to get a halfway accurate reading. If your readings do not make sense, step one is to double the times to make darn sure the mixing is thorough enough. If it doesn't affect your readings, you are one of the few mixing well enough in the first 30 seconds.
As others have already said, plants do use both ammonia and nitrates. Since they will prefer ammonia when they are exposed to both you can lose a part of your bacterial colony to competition from the plants but that's not really a bad thing. It means that you are not totally dependent on the bacteria. If you need to treat for diseases in a way that damages your bacteria, your plants may save your fish from the extremes of ammonia and nitrites by being active ammonia absorbers in the tank. All the stuff we use to tell us what's good for the fish rarely takes into account the benefits provided by a real plant environment.

 

[nitrochicken]

My tank is definately only 29L, it measures only 1' cube approximatley.

My nitrate kit says to add first two chemicals, shake well. Shake 3rd bottle for 30 seconds then add 3 drops. Shake well, wait 5 min, shake well again and read. This is what I have been doing each time I have used it and it has definatley dropped since last week.

Maybe its not such a bad thing, plants using ammonia/nitrate then. I will do a 20% water change tomorrow and every week now.

One of my fish is not looking too well today and I have started anoter post about this.

Thanks

Dale

 

[rabbut]

In part yes, they use it in preferance to nitrite, which they use in preference to nitrate

Aquarium plants don't use nitrite, only ammonia and nitrate. I'm not sure why, but that is the case.

Appologies, I thought plants used both

 

[Bblou]

I read somewhere that nitrate should be 40 or lower. is this right? I htink it was in my test kit actually.