consistently 0 nitrates?

**madagascariensis** · 02-10-2013, 12:32 AM

For the last few weeks, according to my api test kit, my 65 gallon has been consistently having 0 nitrates.
I set this particular tank up about a month ago, with established filter media. for the first week I still got nitrate readings
but after that they just seemingly bottomed out. I am sure that this tank is cycled. ammonia and nitrite are both at 0, I used mature
filter media and all fish and other livestock are in good health and breeding.

the tank is moderately planted, kept at 23.5 °C and filtered by an eheim 2217, substrate is seachem flourite. stock
is 21 white cloud mountain minnows, 11 panda corydoras, 7 otocinclus, 7 endlers, 5 amano shrimp, a ragtag bunch of various nerites and a honey gourami.
could the plants be absorbing all the nitrates? I don't have such a high stocking level but my tank also doesn't have too many plants, and none are established and growing
fast. is the substrate absorbing them? I heard somewhere that plant substrates absorb, store and slowly leach nutrients over a long period of time? I don't think anything in the filter is absorbing it - I took out the carbon 3 weeks ago.
I also don't think something is wrong with my test procedure. I have a 10 gallon quarantine set up and the test consistently is orange when I test that tank by the end of a week but just remains bright yellow with the display tank.

Any suggestions are appreciated - I really am puzzled. it especially worries me that the missing nitrates will affect my plants somehow.

**Cliff** · 02-10-2013, 12:37 AM

I use the API nitrate test kit as well. My tank has been set-up for a few years now and is planted. I vac some of tha gravel each week, clean the filters monthly, and change about 75% of the water each week. I get 0 nitrates according to the test results. There are nitrates in the water, just not enough for the test kit to pick up on.

You might be in a similar situation as I am in.

**CrunchyLeaf** · 02-10-2013, 12:39 AM

My 10 gallon is moderately planted. I often get a nitrate reading of 0 as well with the API Master Test Kit. If I get busy and I skip my weekly water change, I will register 10 ppm nitrates after 2 weeks.

**madagascariensis** · 02-10-2013, 12:43 AM

thanks, although the tank has only been there for a month, my maintenance schedule is quite similar to yours(cliff)

i am planning to eventually add more stock so we'll see if anything changes.

**dmagerl** · 02-10-2013, 01:26 AM

Bottle 2 of the test kit contains tiny zinc particles that settle to the bottom of the bottle and form a big glob. It takes a lot of shaking to get those particle back into suspension. If not shaken enough, a 0 reading results.

I suggest really banging the heck out of the bottle. Wack it on a table top several times or otherwise impact it to get those particles back into suspension.

I've had a 0 reading even when I know there are nitrates and then a retest immediately after shows a normal amount.

**funkman262** · 02-10-2013, 01:39 AM

My local aquarium club actually ran an experiment during one of our meetings held at a university. They had all of the members bring in their nitrate test kits, and each of us tested their solutions with known nitrate concentrations, then we rotated test kits so that each kit was run by two people, and the majority of people got low readings because they make the mistake of not shaking the hell out of the second bottle as dmagerl suggested (although I'm pretty sure it's cadmium, not zinc). If it's been a couple week since I've tested for nitrate, I'll shake the bottle vigorously for like three minutes to make sure it all gets dissolved.

**Cliff** · 02-10-2013, 01:42 AM

+1 to the above two posts

You really have to shake those bottles a lot to make sure your getting accurate results.

**madagascariensis** · 02-10-2013, 01:50 AM

Test procedure might be a problem but as mentioned in the original post I do get credible readings from one of my other tanks. But I definitely will try to shake a little but harder next time.

**talldutchie** · 02-10-2013, 04:31 AM

I'm got 8ppm in tap water. In my current tank I had about 12-15 before the weekly in the first 6 weeks or so. Then the plants really took and that dropped. Then I introduced amazon frogbit and the nitrates now barely register.

So, bad testing is an option but plants growing well will certainly lower nitrates quite a bit. That's one of the reasons why I think real plants beat those strands of plastic.

**mizzoutank** · 02-10-2013, 04:57 AM

Originally Posted by talldutchie

So, bad testing is an option but plants growing well will certainly lower nitrates quite a bit. That's one of the reasons why I think real plants beat those strands of plastic.

Second that.

Nitrates are used up by plants, and are actually part of the ferts to help them grow.

so you have a combo of your plants taking up the nitrates and lack of shaking that bottle.
either way, with proper stocking/pwc schedule, you'll be fine.

i haven't tested my water in 2 months...simply don't need too. the tank is well established, moderately stocked and pwc 50%/week. kinda impossible for something to go wrong (knock on wood)