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Hello peeps.

I would be very grateful if someone could point out the obvious thing I am overlooking and help me figure out the following problem because it has me stumped. :help:

Problem

Over the last three weeks my nitrate reading has been in excess of 80ppm. Judging my API test kit it lands somewhere between 80 – 160 (hard to tell exactly but the vial is bright red – and yes I have looked at it through the top, sides and held it up to different lights). I am not sure why it’s reading so high as this has never happened before.

Facts

Ammonia 0

Nitrite 0

PH 8.4

KH 10

GH 15

Tap water direct from tap reads 0ppm for nitrate

Water changes: 25% every week with new tap water added which has been double dechlorinated and rift lake salts added.

API test kit was bought 6 weeks ago and I shake the bottle before the tests for two minutes and tapped it! and I washed the vials with clean water before and after each test.

Sump consists of filter sponges (blue then black then white filter wool); then bio balls, then 30ltrs of Marine Pure Spheres, then K1, then 20kgs of crushed coral, then 7ltrs of Matrix, then 9ltrs of Macropore and 500ml Purigen then into the pump chamber. (Note: the Matrix has only just been added)

Tanks on sump: 4 (three 6x2’s and a 8x2)

Fish stocking: low

Feeding: Between 5 and 6 feeds per week. They are not overfed and I only use quality food.

Planted tank: no

Sump has been running for about a year, however I have extra added media to the sump throughout the year and the Macropore and Purigen has been cleaned regularly.

Attempt to Problem Solve

After reading the API test kit three weeks ago the nitrate was extremely high. This surprised me so I tested the water out of the tap to see if my nitrate tester was working, and it was, tap water read 0 or close to. So I did a 30% water change, no effect, two days later I did a 50% water change, no effect, then I did another 50% water change and took all the water out of the sump and cleaned all the media, no effect. Now this seems strange because if I did a 50%+ water change surely I would see some difference on the reading, even if it only went down slightly? But no, the readings have all been the same; the vial turns bright red within 5 seconds of shaking it.

Given this information I thought I would test my Tropheus tanks which have side drop filters, i.e. individually filtered tanks. Again the same thing, ammonia and nitrite 0, nitrate 80ppm+? This got me thinking. So I got two tanks, completely emptied them both and filled them up with fresh tap water. I filtered one with existing media and the other one with completely new media. After one day from set up, both tanks read nitrates with 80ppm+.

The only common denominator between all the tanks is tap water, but when I test tap water it reads 0-5ppm. I have asked a couple of people but they are just as stumped. Something must be happening to the tap water when it goes into my tanks whether they are sumped or individually filtered. I understand that the nitrates will rise over time, but surely after doing water changes I should see a drop in nitrates even if for a short period of time? and there shouldn’t be any on a brand new tank with new media.

Solutions

So what have I missed? Is it something obvious? Does anyone have any idea what could be going on or how I can reduce nitrates? All I know to reduce nitrates is to do water changes or add chemicals or add plants. I know AOA does Nitraguard so I may give that a go as water changes are not cutting it.

My theories are:

a) Test kit is stuffed – but how can I get a different reading from the tap to the tank?

B) I have high nitrates because of the number of fish – very doubtful as I have verified this with someone on this forum who is very experienced.

c) Tap water has high nitrates because of high usage over the Christmas period and the water company is messing with the parameters – this is possible because how else can I explain a brand new tank set up having high nitrates.

d) Don’t worry about it and carry on as usual – this has been my thinking over the last week in which I have done another couple of WC’s. My fish seem healthy, they have a strong appetite, no one is hiding in corners, had no deaths, and I have a ton of mouthfuls from various fish in the 8fter (not keeping them they will spit and become food).

Thank you all for taking the time to read this.

Cheers.

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Silly question but when was ur sump last back flushed? I had a similar but not as drastic problem on a small sytem several years ago. Turns out my problem was my 30L of coral bones was clogged with mulm. Gave this a good tumble, in tank water, and was surprised by the amount of crud that came out of it. After that day i cleaned dense bio media 3 monthly to prevent same issue arising again

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[MENTION=495]ronny[/MENTION]. Not a silly question at all I appreciate the help. I did a big back flush about a month before my nitrate spike. Since then I have done another massive clean of the sump and emptied all the water and put fresh back in. Definitely clean media in there. I clean the sponges in the sump every other water change too.

Another thought. About a month before my big nitrate spike I added the 8fter to the existing sump and this is when I would have done the big sump clean. Prior to that I just had the three 6fter's. Could it be my tanks cycled again without me knowing which produced a big nitrate spike? I did not notice any ammonia or nitrites in my previous tests though, but would adding 800lts of water do anything like this?

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Tap water is usually 7.4-7.6 not 8.4....sounds Like bore water and until recently tap was about 20 ppm nitrate so its a bit strange.

Ur test kit could be old or subjected to heat?

Also nitrate is logarythmical ( however u spell it) which means if the nitrate is 50ppm in 100 litres and u do a 50% water change, it won't drop by 50%.

You could try nitrate remover sponges ect.

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Thanks mate. I should clarify the PH is 8.4 in the tanks because of the rift lake buffer I add. I did not test PH out of the tap, just the nitrate.

Test kit is six weeks old, yes it could be producing silly results so will take a sample to the LFS either tomorrow or Friday.

I get that if I do a 50% change that the reading won't drop by 50%, but it should show some kind of decrease right? or will I always be reading a high nitrate regardless of how many/big water changes I do?

I shall look for nitrate remover sponges, thanks.

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You can simulate the effects of water changes with a 20L bucket.

Eg add 10L of aquarium water to bucket and then add 10L of tapwater = a simulation of a 50% water change.

I would simulate various % water changes until you see what it would take to get below 40ppm.

I suspect the problem started when you added the 8 footer to the system. Likely high nitrates in that tanks water.

Well worth double checking the kit though.

Remember nitrates are much less toxic than ammonia or nitrites...... so not an emergency.

I really slowed down nitrate build up in my display using carbon dosing (nitraguard) as I was getting over the big weekly water changes on it.

Edited by Donny@ageofaquariums

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You can simulate the effects of water changes with a 20L bucket.

Eg add 10L of aquarium water to bucket and then add 10L of tapwater = a simulation of a 50% water change.

I would simulate various % water changes until you see what it would take to get below 40ppm.

I suspect the problem started when you added the 8 footer to the system. Likely high nitrates in that tanks water.

Well worth double checking the kit though.

Remember nitrates are much less toxic than ammonia or nitrites...... so not an emergency.

I really slowed down nitrate build up in my display using carbon dosing (nitraguard) as I was getting over the big weekly water changes on it.

Nice idea Donny, very nice indeed. I shall do some experimenting tomorrow if the kids give me a spare hour :) The 8fter was added as a new addition, in other words it was a brand new tank with new substrate, décor and 800+ litres of water straight from the tap, double dechlorinated etc, unless of course at the time the tap water consisted of high nitrate. My problems started not long after adding the 8fter, coincidence? This is a picture of the test results two hours after doing todays water change.

post-11719-14711632932415_thumb.jpg

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Tap water is usually 7.4-7.6 not 8.4....sounds Like bore water and until recently tap was about 20 ppm nitrate so its a bit strange.

Ur test kit could be old or subjected to heat?

Also nitrate is logarythmical ( however u spell it) which means if the nitrate is 50ppm in 100 litres and u do a 50% water change, it won't drop by 50%.

You could try nitrate remover sponges ect.

Please explain.... pH is log function. nitrate is ppm so 50% water change should half unless something in the new water.

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Wow thanks for your input guys. I tested my tap water and it also reads 0 so don't think it's my test kit but will take a sample to my lfs anyway, won't hurt to get it checked.

Donny I don't think I overfeed. 5 to 6 feeds a week and the food i put in is usually eaten within 30 seconds. I do feed my frontosa's NLS Thera A+ and this is by far the messiest and leaves particals everywhere. I used to feed this exclusively but now every third or fourth day because of the mess it leaves. I also feed them New Era Red and frozen foods - krill, brine shrimp, mysis etc.

I will get my water tested and go from there.

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The only things that I can see as being different is the addition of the salts.

Might be interesting to see what results you can get if you test tap water, tap water dechlorinated and tap water dechlorinated with salts added.

Might be best to do this after getting your water tested elsewhere to make sure that the test kit is reading accurately.

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The only things that I can see as being different is the addition of the salts.

Might be interesting to see what results you can get if you test tap water, tap water dechlorinated and tap water dechlorinated with salts added.

Might be best to do this after getting your water tested elsewhere to make sure that the test kit is reading accurately.

Another great idea as I will be able to rule out certain things to get a narrower idea of what is going on. I will do this when I test Donny's water change idea. Great input guys thanks.

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[MENTION=353]Rod[/MENTION] thanks a million mate, this is a great idea and gives me a weekend project. I must admit I have zero algae in my system due to the placement of the tanks and the limited light it gets. I have just the place in my sump where this could be utilised. Thanks.

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I'm a total noob, but is it possible there is something dead and rotting in one of the tanks? hidden under a rock/ornament?

Tanks are brand new (two months old) and all my money went on the tanks, rack, substrate and new sump pump. I had very little left over to add anything in the tank, lets just say I am going for the minimalist approach at the moment ;) So if anything dies it would stand out so much that even Stevie Wonder would spot it :) Awesome suggestion though.

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