High Nitrate?

[mnewsholme]

I'm about 14 days into a fishless cycle. Been testing ammonia and nitrite to timetable suggested and everything appeared to be going ok. Started seeing nitrite on day eight and ammonia dropping. Day ten nitrite over 5ppm and no ammonia so added second full ammonia dose. Hadn't been testing nitrate uptil now, but got nitrate test and tested today and it appears to be 100+. Next ammonia and nitrite test is due tomorrow. Gonna retest nitrate then at same time and also check tap water to get a baseline and also to see if nitrate test is ok. My Theory being if it says tap water is 100+ then test kits probably a dud.
Tank is planted 200l with four or five root tabs in for plants. If nitrate checks high again should I do a partial/full water change? Ph was 7 when I did last ammonia and nitrite check. Will check that tomorrow too.

Any suggestions how to proceed gratefully received.

Matt

 

[Blondielovesfish]

High nitrate is rather common for fishless cycling, I'd just leave it and wait until the cycle is complete to do your big water change, as it will just keep increasing as the ammonia and nitrite is processed.
 
If you pH starts dropping, however, it would be best to do a water change, because sometimes when the nitrate gets really high, it converts to a type of acid (forgotten the name of it) which drops the pH.

 

[paradiddle]

Dont forget to test your tap water too, a thing often forgot by new hobbyists
i already know my tap water is high in nitrates

 

[mnewsholme]

Done full tests today.

Tap water tests as ph 7-7.5, nitrate 0

Tank water test as ph 7-7.5, ammonia 0, nitrite 5ppm (maybe a little lighter than last test so think it's dropping), nitrate somewhere between 50-100. Think I need to leave and retest in two days. Then give 1/3 ammonia dose as snack and keep waiting for nitrite to drop?
Some of plants died off a bit and lost some leaves in first week before I added the root tabs. Could this have been source of high nitrate. New growth coming through on all plants now though.

Matt

 

[TwoTankAmin]

Stop testing for nitrate. All it does it make you react as you have. That test isn't worth the cost of the parts, the results are worth slightly less most of the time.
What counts is nitrite and ammonia.
 
Plants eat both ammonia and nitrate but prefer the former. They don't eat nitrite. But here is a flash. if you have not done a water change since you started the cycle, you can calculate the most nirtate you can have based on the ammonia put in. Since you still have nitrite, that has yest to be converted .
 
1 ppm of ammonia makes 2.5 ppm of nitrite and then 3.44 ppm of nitrate using an API kit based on the total molecular weights of NH4, NO2 and NO3. In fact, the more of the ammonia that is NH3 the bigger the two other numbers become, but by so little it doesnt make sense to bother calculating for that. NH4 is 18.04 and NH3 is 17.03. Since the absolute most one might see NH3 at would be 10% of the total ammonia, the weight would still only be 17.94. Anyhow,
 
Take all the ammonia ppm you have added since the tank started and multiply it by 3.44. Then test nitrite accurately and multiply the ppm for that by1.34 and subtract it from the first total. This is the most nitrate you could have. It assumes 0 ammonia and 0 nitrate was taken up by the plants.
 
To read 100 ppm of nitrate and currently having 5 ppm of nitrite I can work backward. But first because of how the kit works, we need to subtract the amount of nitrite present from the nitrate tested, so 100 - 5 = 95 ppm. 95 ppm nitrate - (5 ppm nitrite x 1.34)/3.44 = ppm ammonia . Or,
 
95 - 6.7 = 88.3/3.44 = 25.67 ppm of ammonia went in. I do not think so??? If the Nitrate is only about 50 ppm, then about 13 ppm of ammonia went in. That would be 4 additions of 3 ppm and a 1 ppm dose.
 
But it's all silly because I bet if you test nitrate twice about 30 minutes apart you will get different results.
 
it is typical for plants to suffer transplant shock. They lose some or even all leaves but the key is whether or not one gets new growth.

 

[mnewsholme]

Cheers Twotankamin. That puts my mind at rest. Getting plenty of new growth on plants so will just keep checking nitrite every couple of days as per schedule and ignore nitrate.

Matt