Shocked on nitrate readings

Around 6 months ago, I ran out of my test kit liquids, and I did not have the finances to replace.

My tank is a 200 litre with 3 x fantail goldfish with java fern, heated to 18 C, 1440 litre per hour external canister, with a small booster filter. Booster filter does the mechanical filtration, which I clean when the flow rate starts to reduce, and my external canister is full of around 3.5Kg of Biohome media. This media had been in for around 12 months before I stopped testing water parameters. Prior to this, my weekly readings were always 0 ammonia, 0 nitrites and around 40 nitrates. I thought I had fallen for the biohome spin, as I saw no noticable drop. Whilst having no test kit, I kept to my winning formula of a weekly 50% water change.

Today, my new test kit arrived. Aquacare Pond Master Test Kit. Slighly different to the API kit I previously had, with subtle shades of pink for between 0 and 40 nitrates.

Tested the water first thing today and the result was hard to gauge, but either 5 or 10 nitrate reading. Was shocked to see such a low reading. I did my 50% water change earlier and retested. A very slight pink tinge, I would say 2.5, which would make my first reading today 5ppm.

In the 18 months I have had this tank, I have never had such low nitrate readings. Java Fern is rather slow growing, so I cannot see it being that which is using all the nitrates.

I am wondering if my biohome media is actually doing what it is supposed to be?

 

Most likely change in test kit brand.... I honestly can never tell mid-levels... only low or high. Mines always around the 20ish range (I think).

You might have reduced feeding without realising it. I certainly change my feeding routine over time.

 

Biohome is supposed to take quite a while to get going. I’m glad you retested to be sure. When Nitrates are real low (especially near a scheduled WC) it’s either great news which this probably is or a potential concern. I‘d also suggest….just for kicks….to again test your Ammonia and/or Nitrites. Just being careful due to your 2-5 NO3 results which are remarkably low for Goldfish.

 

My fish are now fed up with being disturbed, so will do ammonia and nitrites again tomorrow. Were both 0 and 0 this morning.

What I have done though is a diluted nitrate test - 1 part tank water to 4 parts tap water (nitrate free). The tube is crystal clear.

So if my previous reading was 2.5, dividing this by 5 would give me 0.5
If my previous reading was 5, dividing this by 5 would give me 1

These 0.5 and 1 would probably give zero readings in the diluted tube

If my previous reading was 10, then I would expect to see some pink tinge on the diluted test and definately some pink tinge if the previous reading was 20.

So it does look like my readings were around 5 pre water change and 2.5 post water change.

 

“What I have done though is a diluted nitrate test - 1 part tank water to 4 parts tap water (nitrate free). The tube is crystal clear.”

Plz explain, for me, why you do a diluted test. I would think it would be easier and more accurate to measure your exact tank water. I’m not trying to do anything more than find out your reasonings.

 

With a diluted test (1 part tank, 4 parts tap), the tube result will be 1/5th of the actual result.

I can then work backwards to gauge possible readings. ( I am a maths teacher, so I like to play around)

With my diluted test, the result would have to be multipled by 5 to get the true result. So if my diluted test showed a reading of 5, then the actual true result would be 25).

My first reading this morning I thought looked to be 5 - but this gave a pink tinge.

My post water change I thought looked to be 2.5 - this gave a slight pink tinge.

As my diluted test gave no noticable pink tinge, then my previous two readings could not be 10 or more, as a 20 reading would not give a clear diluted test (20/5 is 4 and both 2.5 and 5 gives a tinge) and 10 would probably not give a a clear diluted test (10/5 is 2, which is very close to 2.5 and 2.5 gives a tinge).

I used this test when I was cycling the tank, as my readings were off the scale due to cycling with a prawn I bought from the supermarket (it gave off more ammonia than I had anticipated). Did a diluted test which showed up on my API test strip and multipled the result by 5.


But without doing an accurate test, the above is just an hypothesis.

 

Ok, I get it. I am a retired biology teacher, certainly not a math guru. And….to each his/her own. Being in the sciences, it would seem to me ideal to test the actual water at 100% so there can be no mathematical miscalculations, it would be easier/take less time, and I’d think the test would better pick up higher concentrations as opposed to such a weak solution. But…..I’m not trying to sway you and you nicely explained for me why you do the dilution thing…..thnx.

 

One of the tanks over here is a similar water volume tank as yours non planted. It's got 4 juvenile fancies in it. Filter has Matrix Media in it running at a low flow for about 8 months or so with this current setup. Average nitrate weekly accumulation is about 2.5 to 3 PPM nitrates. Weekly 40-50% water changes are really just done to clean up poop on the substrate and to keep PH in check. So yes...I can believe your readings are possible.

This was the NO3 test right before the WC today.





Major poop machines just after less than a day prior them stirring it up. So you can see imagine how much waste there is after a week.

 

One of the tanks over here is a similar water volume tank as yours non planted. It's got 4 juvenile fancies in it. Filter has Matrix Media in it running at a low flow for about 8 months or so. Average nitrate weekly accumulation is about 2.5 to 3 PPM nitrates. Weekly 40-50% water changes are really just done to clean up poop on the substrate and to keep PH in check. So yes...I can believe your readings are possible.

This was the NO3 test right before the WC today.

Major poop machines just after less than a day prior them stirring it up. So you can see imagine how much waste there is after a week.

Thanks……that’s good to know. Nice levels to have. I’m a believer/user of both Matrix and Biohome. My levels are pretty good, but not yet that low.

 

One of the tanks over here is a similar water volume tank as yours non planted. It's got 4 juvenile fancies in it. Filter has Matrix Media in it running at a low flow for about 8 months or so with this current setup. Average nitrate weekly accumulation is about 2.5 to 3 PPM nitrates. Weekly 40-50% water changes are really just done to clean up poop on the substrate and to keep PH in check. So yes...I can believe your readings are possible.

This was the NO3 test right before the WC today.

Major poop machines just after less than a day prior them stirring it up. So you can see imagine how much waste there is after a week.

Left is Nitrates, Right is Nitrites.

The API chart is much clearer for very low nitrates.

 

I was beginning to think that maybe my test kit was faulty. Filled a cup with tank water and left it in the kitchen with some fishfood in all week.

The first three tubes (left to right) are my ammonia, nitrite and nitrate reading (today) from the kitchen cup. I estimate the cup nitrate reading to be about 10.

The final tube is today's reading from the fish tank. It is perfectly clear. I will say there is 5kg of biohome ultimate in my filter - as I used to have two tanks, before a summer house move.

 

this guy says he did an experiment, no difference using biomedia

 

It seems that it was not the Ultimate that was keeping my nitrates very low, but my water conditioner (Natural Rapport).

I needed a new bottle, but could not get Natural Rapport, so I purchased some API tap conditioner. Natural Rapport binds Ammonia, Nitrite and Nitrate. The past couple of weeks, since using API, my nitrates have been rising around 20 every 3 days.