Nitrate Readings Unbelievable

[HappyGeorge]

I have just set up my tank.

Tap water chemistry - pH 8, Nitrates 10

Its a 450 litre containing some river cobbles and Kentish ragstone which is very hard and weathered and shouldn't be contributing to tank chemistry, it also has a DIY cement background.

I have had the tank full of water for 2 weeks with an internal U4 filter running, but no water treatment or ammonia. During this time I emptied and filled the tank by 80-90% 5 times, this was to ensure the background wasn't going to do anything nasty to the water and to completely finish curing it.

On Saturday I put in fresh water and conditioned it heated it to 28-29 degrees, then added Nutrafin Cycle and ammonia to 6ppm and turned on my Fluval FX5 filter, which is running with 2 baskets of bio one topped with a polishing pad and one with some pond filter, with the 3rd basket empty.

Tested on Sunday - 28 hours later, and was getting a Nitrite reading of 0.3 - this seemed a bit quick for the cycle to have started.

On Tuesday I met with Glolite who gave me a nice dirty sponge in exchange for a nice shiny new one which went straight in the FX5.

I tested the water last night and had the following readings

pH 8.6, Amonnia 3.7, Nitrite 1.6, Nitrate 50.

This just does not seem right. I dosed back up to 6ppm on Ammonia and then sat scratching my head.

I retested with the same results and this morning put some cement in a bucket and tested that just to make sure it wasn't the background. The reading that came back from that was the same as the background level straight from the tap.

So I'm stumped, anyone got any clues please?

 

[rabbut]

Quick cycle? It's not really too quick, as you only saw 0.3ppm Nitrite from the tap after 48 hours, which is about what I got when I cycled my 335l tank... A nice seed from mature media could easily have pushed your cycle onto the speed you have now

 

[drain_bamaged]

and if the Cycle product has worked, that obvioulsy would have helped!

 

[loraxchick]

agreed. fast cycle for you. lucky duck!

 

[HappyGeorge]

Following the dose back to 6ppm Wednesday night.

I just tested the water with the following readings.

pH 8.4, Ammonia 0.3, Nitrite 1.6. Nitrate 110

Do you think I should do a partial water change or is it fine for the bacteria to be in water that high in Nitrate.

So thats from 6ppm to .3ppm in 44 hours is that getting close to a reasonable time and are my Nitrate tests being affected by my high Nitrite levels or vice versa?

I have just dosed back up to 6ppm again.

AMMENDMENT - Just came back to the tests and the nitrate is now looking like 10ppm think I read it too early as in a hurry.

Would the high Nitrite readings have caused the high reading on Wednesday, seem to remember something about test readings being skewed by high levels?

 

[rabbut]

Most Nitrate test kits work by converting the Nitrate back to Nitrite and then testing for Nitrite. For this reason, your Nitrate reading will probably be falsely high if Nitrite is present. If the pH isn't crashing, I'd let it be. If it ain't broke, don't fix it

 

[OldMan47]

One observation. Stop dosing the ammonia so high, you will end up with the wrong bacteria developing if you go over about 5 ppm.
Your use of a mature filter sponge might well have you processing lots of ammonia and nitrite fairly quickly like that. There is no harm to the nitrate build that you are seeing unless it causes a pH crash. Since part of the nitrate is in the form of nitric acid, that can happen if levels get too high. As Rabbut said, nitrate test kits can be affected by nitrites present in the water and until both ammonia and nitrites are processing well, there is not much point to testing nitrates except to get some practice doing the test. Eventually the nice starter colony of bacteria that you have will grow to the point that they can process 4 or 5 ppm to zero ammonia and zero nitrites in 12 hours. You do have a nice start but are not close to that degree of being cycled yet.

 

[rdd1952]

Keep in mind that ammonia:nitrite:nitrate isn't a 1:1:1. It's 1:2.7:3.7. So 1ppm of ammonia will become 2.7ppm of nitrite and eventually 3.7PPM of nitrate. Even at that though, it would take about 30ppm of ammonia to get to 110ppm of nitrate. Are you sure you weren't severely over 6ppm of ammonia from the start?

 

[HappyGeorge]

Keep in mind that ammonia:nitrite:nitrate isn't a 1:1:1. It's 1:2.7:3.7. So 1ppm of ammonia will become 2.7ppm of nitrite and eventually 3.7PPM of nitrate. Even at that though, it would take about 30ppm of ammonia to get to 110ppm of nitrate. Are you sure you weren't severely over 6ppm of ammonia from the start?

No the dosing was definately about the 6ppm mark used an online converter and checked the maths myself, if anything it was under as I made allowances for the water displacement by rocks, it also tested at under 6ppm.
I would also be interested to read anything people have on the net regarding development of the wrong bacteria that Oldman was referring to, the only articles I have read relate to the bottled bacteria cycle starters/boosters being the wrong strains of the species responsible for the breakdown of nitrites/nitrates, and just wondering if this has happened in my tank, the articles I found also only related to these being theories so some lab results would be interesting.

As I listed it did retest at 10, and think the previous reading was down to the effects of high nitrite levels.
I was a little confused by the initial readings as I thought it was all a bit quick but I think the answers on here were in line with the conclusions I had drawn.

Thanks everyone I think I'm getting there but maybe not as quick as I had first thought.