Hi

I'm really confused, after having discovered the nitrates in my tap water were 40ppm, I bought a nitrate remover for the tap water. I did several changes of 30%, tested the tank and it came about about 10ppm - as you would expect.
I did another water change last night, 30%, using the filtered water but today my tank is back up to between 30 and 40ppm. Ammonia, nitrite zero.
I struggle to read the API kit anyway, the shades of orange are so similar but it is definitley in the darker region than it was on Tuesday when I last did it. Is there a way of getting the test wrong as I just can't fathom how after a 30% change of nitrate filtered water the reading can increase?
What is going on?

Hi Beannikki

I just wanted to agree with you, I really struggle reading the api nitrate test readings as well..

Some of the colours are so similar it can be hard to read them.

Ella

The nitrate test is notoriously difficult to read, and is very sensitive to any variation in the test procedure. It's really important to follow the directions precisely to get an accurate result.

It's especially important to give Bottle No2 a very vigorous shaking for a full 30 seconds before using it and it helps to bang it down hard on a worktop or similar. If it isn't shaken enough some of the components of the test solution settle in a sediment at the bottom and then results are inaccurate. Over time, it becomes more inaccurate as each time it's used, more of the sediment remains in the bottle and alters the composition of the chemical.

The other vital part of the test is to ensure you shake the test tube for a full minute after the drops from bottle 2 go in.

HTH

EDIT: Do also test the water produced by the filter from time to time to check whether it's time for a recharge

Thanks Noodle

I'm sure I've been doing it correctly but I haven't been banging the bottle on the worktop, just shaking it so will try that.
Am I right in thinking that you take the reading after 5 minutes even if it goes darker on standing for longer? I've noticed sometimes if i don't empty the test straight away it seems to be darker after a while.

Yes read it after exactly 5 minutes .... any sooner and the colour may not have developed fully, any longer and it's beyond the test tolerance so is less accurate.

Quote:

Don't do what I did - I left my ammonia test in the tube for a couple of days and now the tube is stained yellow which makes it more difficult to read

Hi everyone

The mystery deepens. I've run some water through the filter and tested it, comes out close to zero nitrates so I know the water going in is low nitrate.

Tested tank again and given bottle 2 the shaking and banging of its life, read after 5 minutes exactly, still reading near 40ppm.

Why is this happening? The tank has had 4 changes with filtered water with a strating point of 40ppm nitrates, how can it still be this level despite reading much lower Tuesday???

Lets rewind a bit and try to figure it out

If the level in the tank read 40ppm when you first started using the filter, how had you managed to reduce it to that level?

How much water (approximate number of litres) have you changed using the filtered water since then and over what period?

Just to save me looking, how much water does the tank hold?

Hi Noodle

Tank is 135 litres - 10% = 120 litres.

Tank started at 40ppm (as best i can tell with the API kit
Using filtered water ).

Water change 1 was Saturday, 30 litres
Change 2 was Monday, 30 litres
Tested tank at 10ppm (again as best as I can tell)
Change 3 was Wednesday, 30 litres (wanted to be sure I'd got nitrates right down)
Tested tank today and nitrates near 40ppm - not quite but almost).

All water added to tank treated with Prime. No ammonia/nitrites on all tests.

OK. Well right at the beginning I think the test result of 40ppm is suspect. As your tap water has 40, the tank, if cycling corretly with a Goldie in situ MUST have been highr. Because the end product of the cycle is nitrate, the level in the tank can only ever be more than that from the tap unless you have masses of plants - and with a Goldie eventhat wouldn't be enough to keep the nitrate level down.

Also, when you first posted here you had ammonia readings, so it's likely the fiter wasn't coping at that point - now that it is, the amount of nitrate being produced will have increased.

With 120 litres and assuming it was actually only at 40ppm for the sake of calculation, the first change would have removed 25% of the water and replaced it with water at 0 nitrates. That would reduce the reading to 30ppm. The second change on Monday would have reduced that by 25% again, from 30ppm to 22.5ppm, but from Saturday to Monday, more would have accumulated so it would actually have to have been higher than that. As your test on Monday gave a result of only 10, something must be amiss with the testing.

I reckon the staring nitrate was higher than you thought, and that taking into account reaccumulation between water changes and the cycle being properly established (as seen by 0 readings for ammonia and nitrite) the most recent reading of just under 40ppm is most likely to be correct.