Consistently High Nitrate

[laurac94]

Hi all,
So today I found one of my mollies dead (no symptoms) so I did a full water test which went as follows:

pH: 6.2
Ammonia: 0
Nitrite: 0
Nitrate: 80

This has been going on for a couple of weeks now and I have been doing 50%ish water changes twice a week to try to reduce it.
I just have bogwood in the tank but no plants, should I get some to reduce the nitrate?
What is causing such high levels?

The tank is 40 gallons with 6 mollies, 4 neon tetra, 8 serpae and a 6inch common pleco

At my last water change 2 days ago I rinsed the filter media in old tank water and swapped some of the really old media with some cycled ceramic rings from my piranha tank. I did the tests today.

 

[techen]

What is your tap water nitrates?

 

[Lillefishy]

Have you tested the tap water?
Run some off & leave overnight then test it to see if it has high nitrates.
Also what test kit do you use? If the Api one the nitrate bottle has to be shaken really really well sometimes to get an accurate reading.

Edit: I forgot to say have a look on your local water companies website they usually have a chart showing what's in your local water

 

[laurac94]

I use the API fresh water kit, and I made that mistake when I first got the kit by not shaking the bottles enough a few months ago ;-)

So I follow the instructions now lol
The tap water is testing at 0 for nitrate, my other 2 tanks give 10 and 20 for nitrate so nothing as high as my community tank.

I will test again in the morning with some stood water, just confusing how it can go so far up consistently, not had any problems before and the tank has been running for over a year now.

 

[Lillefishy]

Are you adding any plant fertilisers?

 

[laurac94]

Nope, I dont have any plants so no need to, literally just bogwood, gravel, fish, filters and a heater in the tank. The only thing I add to the water is API stress coat to dechlorinate it ;-)
I suppose plants would love my water as it is ;-)

 

[Lillefishy]

Plants would love it & help bring down the nitrate.
You could have easy ones like amazon swords, moss, anubias etc

 

[TwoTankAmin]

A cycled tank is one that clears ammonia and nitrite to nitrate without showing ammonia or nitrite on the way. A samll tank with a few fish or a huge tank with monster fish, it is the sames in terms of the process. Where the tanks are not the same is how much ammonia they produce and thus how much nitrate wither tank ends up showing.
 
Your 40 gal has an ammonia factory in it in the form of a common pleco. So this tank makes much more ammonia per day than your other tanks which means in the end, it makes way more nitrate in the same amount of time.

 

[laurac94]

So should I sell the common pleco? I was thinking of selling him anyway because he will be way too big soon (he was sold as a bristlenose when I was a newbie)
I might put it in my 55 until I can sell him then, would that be the best move? I will do it tomorrow along with a large water change to reduce the amount of nitrate
I can pick some plants up on Tuesday, something fast growing like pond weed? I have no experience keeping plants at all so I wouldnt really know where to start keeping more demanding ones.

 

[TwoTankAmin]

You don't need demanding plants, you need just the opposite.  Stem plants- you can even float them.
 
But you can just do twice a week water changes and will be fine for a while. I would rehome the pleco out of your tanks completely, but no need to panic about it. If you throw it into another tank, you will likely get a mini cycle to bring that tank up to snuff re the bacteria colonies.

 

[laurac94]

Ok will get some fast growers and try to rehome the pleco in the next few weeks, need to find the right home first ;-)
Thanks for the advice.. Lets hope it works! ;-)

 

[Zante]

Sorry of I'm going a bit off topic here, but isn't a ph of 6.2 a tad low for livebearers? I thought they'd be happy on the other side of neutral, and it's not what I'd call a small difference...

 

[laurac94]

Yep I know, I tried to get it to go up for ages and ages with large water changes, my tap water is something around 7.2 -7.4 and somehow as soon as it hits my tank water it immediately drops. The mollies are all really active so they don't seem to be bothered by it. I am not a fan of chemicals so since they are all healthy I just left it as it is.
Any ideas on how to get that up too?

No idea why it is just this tank that plays up ;-) my other 2 are perfect and this one gets the most attention from me lol ;-)

 

[Zante]

Hmm... The easiest way would be to use kalkwasser, I'm not sure how it would work in freshwater though, it is commonly used in reefs to raise and buffer the ph, as well as adding calcium to the water. In theory it should be fine, but I'd wait for someone who has actually tried it. I actually have the opposite problem that you have!

 

[levahe]

It could be the bogwood lowering your pH, do you have a large amount of bogwood in the tank? I wouldn't worry about it too much though if your fish are OK.
As for the nitrates you say its been going on for a couple of weeks? Was it fine before that? Is there a dead fish stuck in/behind some where, that could cause it and do you do gravel vacs every now and then?