Fertilizers and Nitrate Readings

[Tien23]

I am experienced in the aquarium hobby but am new to planted tanks. I have a Fluval Ebi 8 gallon shrimp tank that I have heavily planted. I occasionally dose Flourish, Iron, Phosphorus, Potassium, and Excel. I want to maintain decent plants without insane levels of growth. So far I have been successful. I also keep shrimp but I am worried about my Nitrate readings. I always seem to have high nitrates. I have less than 10 shrimp and I feed them only once every 2 or 3 days and very little at that since they eat the algae and plant matter in the tank as well. I have been doing water changes because my nitrates have been so high but my goal is to have the plants reduce nitrate levels. My nitrate readings range from 40 to 80 ppm!!! My tap water has less than 5 ppm. Could my fertilizers be affecting the test kit?

[Hoppy]

Any time you are going to make major changes based on test kit readings you need to calibrate the test kit first. Otherwise you can easily be heading in the wrong direction with the changes you make. No test kit, at any price, is guaranteed to give you an accurate reading without first calibrating it. In fact all measuring equipment has to be calibrated when the measurements made with the equipment are important. Hobby test kits are largely for fun, perhaps reasonably accurate at picking up changes, but of little value for absolute measurements.

[Tien23]

I considered buying an electronic nitrate tester but they are close to $300!

[astrosag]

Unless you're planning on building one those pay-to-visit aquariums in your house, I don't think this hobby requires that level of precision lol.

[150EH]

The nitrates are comming from the ferts your dosing, cut back and it will go down.

[DarkCobra]

Originally Posted by 150EH

The nitrates are comming from the ferts your dosing, cut back and it will go down.

None of the fertilizers Tien listed are a significant source of nitrogen.

Given that and the low bioload, it's likely the test result is simply wrong.

[Tien23]

Originally Posted by DarkCobra

None of the fertilizers Tien listed are a significant source of nitrogen.

Given that and the low bioload, it's likely the test result is simply wrong.

Thats what I would think but I verified it with 2 different API test kits. I have never liked those test kits though. I think they are very inaccurate. I took a water sample from another tank to my LFS and they said high nitrates. I went home and used the same brand kit to find significantly better results. I have a nitrogen fert but I do not dose it at all and Flourish doesn't contain nitrogen.

Let me ask this, do the plants I have listed sound like enough to control nitrates for 8 gallons in a small bio load?

[DarkCobra]

I don't see a plant list, only that it's heavily planted.

It could be possible your substrate is sourcing nitrogen. Just to be sure, what substrate do you have? Any root tabs, plant spikes, or Osmocote added?

[astrosag]

What is the acceptable upper limit in nitrate levels for shrimp/fish - around 20ppm no?

Unless you have only mosses, most plants are nitrate hogs. Like someone else mentioned, they eat it up like candy.

I can't see it being anything aside from bad reading or ferts (unless your substrate it leeching nitrates), Try cutting back for a week or two and see what happens.

[Tien23]

Originally Posted by DarkCobra

I don't see a plant list, only that it's heavily planted.

It could be possible your substrate is sourcing nitrogen. Just to be sure, what substrate do you have? Any root tabs, plant spikes, or Osmocote added?

My substrate is Fluval shrimp stratum:

http://www.amazon.com/Hagen-12685-Fl.../dp/B004J4IQXG

Plants in this 8 gallon:

I have one Anubias Barteri Var. Nana which I now hear may be toxic if I trim the leaves in the water. I have probably 30 percent of the tank covered in Creeping Charlie (Micromeria Brownei). Also have 2 large Wisteria bunches, a Java moss ball, tons of duckweed, 3 bannana plants (Nymphoides aquatica) and Micro Sword (lilaeopsis brasiliensis) covering the front foreground of my tank.

[DarkCobra]

Plants sound good, at least a couple of nitrate hungry ones in the bunch. I don't know anything about that particular substrate.

[plantbrain]

Originally Posted by astrosag

What is the acceptable upper limit in nitrate levels for shrimp/fish - around 20ppm no?

Unless you have only mosses, most plants are nitrate hogs. Like someone else mentioned, they eat it up like candy.

I can't see it being anything aside from bad reading or ferts (unless your substrate it leeching nitrates), Try cutting back for a week or two and see what happens.

I dose 45 ppm every week and have for perhaps 100 species of fish, breed them too. Cory's Sturisoma, several other lesser common rare plecos, and catfish, Discus, Angel fish, Apisto's etc.

We do not KNOW what the upper ranges are for NO3 from KNO3.
I've gone up to 160ppm for about 1 month. No issues.

Carmargo et al, 2005 did a decent review of nitrate toxicity, guppies and other warm water species had very high LD50's for NO3. Cold water fish are more sensitive to NO3, since few keep cold water tanks and plants, this cannot and should be used a metric eg, Trout fry are not the same thing.

Still, dosign errors can occur and many have over the last 20 or so years with KNo3...........no one has ever killed fish as far as any confirmed cases I've seen to date with KNO3.

CO2?

Almost every week someone gasses their fish, and that's just the honets folk who admit to it.

No one seems to give a rat's hind quarter there.

Still, a target of 10-30ppm for the plants is adequate for most all cases, I add about 45ppm, but some of this is removed as the week progresses, so it's likely around 20-30ppm range.

Not that targeting that ppm range is all that difficult.

[Chris767]

+1 to the above

I just had some guppy fry, and my liquid test kit is showing 80-100ppm of NO3, the fry have been going for 4 days, haven't lost a single one.

I've worried about NO3 as well, but I'm slowly coming to the conclusion that most fish are highly tolerant of these types of levels.

[astrosag]

Thanks for the reply Tom.

[roadmaster]

I have been dosing KNO3 for nearly a year and a half in planted tank and Nitrate level's according to API test are 40 to 80 ppm. I simply put the test kit away.
Fish and plant's are thriving.
Big difference in my view between nitrate reading's from KNO3, and Nitrates from breakdown of organic waste (ammonia to nitrites to nitrates).