Really high nitrate uptake

[ccLansman]

Im having a hard time figuring out my tanks nitrate intake. For months now I have followed the EI method for my 60gal and use 2 tsp of KNO3 every other day. So I decided to test my water the other day with the aquarium pharmaceuticals nitrate test kit. To my surprise I was sitting at 0ppm according to the kit. As we all know unless we calibrate and so forth we can’t be 100% sure but when we are supposed to be near 20ppm I can’t see the test kit reading 0ppm if there was 20ppm. So I made a small stock solution and dissolved a very small amount of KNO3 and tested this water, sure enough the test kit registered 10ppm (so I know it’s able to register NO3 at least). So I started dosing 3tsp KNO3. Tank starts pearling at lights on, everything looks good.... A few days go by and I notice less pearling into the afternoon. So I dose as normal in the morning 3 tsp KNO3 and wait until the afternoon and test the water with the test kit. To my surprise it says 0PPM! My tank is filled with plants but I would not say heavily plated when compared to a ada contest tank (Every square inch is covered with plant).

So is it typical to have this high of a NO3 uptake if all other conditions are good? Is there something possibly removing it? Does dissolved NO3 sink to the bottom typically or stay in the water column? I’m not using any activated carbon so I know it’s nothing to do with that.

Tank specs:
Pressurized c02 with modified external pvc reactor.
4x65W Pc lights on 10hrs(2hrs 2x65, 8hrs 4x65)
EI dosing per 60gal
Large plant load
Only a few fish to clean up any algae (SAE’s, ottos)
Eheim 2026
Fluval 305
Koralia 1
No name 350gph pump

Thanks guys!

 

[VaughnH]

You have a very high light intensity, you are providing CO2 to the plants, and fertilizing them, so they are going to grow very fast, consuming nutrients as they grow. I think it is normal for the nitrates to be used quickly, but 3 teaspoons a day? That does seem abnormal. Perhaps your test kit is not reliable at all?

 

[ccLansman]

that was my first impression but i would think a company as wide spread as aquarium pharmaceuticals would have a little quality control. Also i do notice a very large increase in pearling after adding the KNO3 when it reads 0 ppm on the test.

 

[tedr108]

At first I thought no way your uptake could be that high, but with tons of plants and no fish load, perhaps it makes complete sense.

I have the same NO3 test kit as you (API). I also calibrated mine with a 10ppm solution that I made -- orange (10ppm) was the easiest color for me to eyeball. Mine was very accurate.

I've always had a rather high critter load in my EI tanks -- heck, even in my non-CO2 tanks, I tend to get a little carried away on critter load. So, I've had no experience with unloaded tanks. Do you have any floating plants? Some of them really use up the NO3, and you may want to avoid them, if you wish to cut down on NO3 dosing. When I was having a little trouble with a non-CO2 tank's NO3 buildup, a few floating plants really seemed to knock it down.

It seems that you have a very good feel for what is going on in your tank, even without the test kit. Sounds like things are going very well.

 

[JDowns]

If your test is reading 0 with the API kit. I would suspect one thing. The second reagent tends to solidify to the bottom of the bottle. You can knock the bottle on a hard surface and try and break it up, then make sure you vigorously shake the bottle for at least two minutes. Also make sure you shake the final test solution for 30 seconds.

API is probably the worst for nitrate, I would rather use a test strip than API's solutions. If you must have a hobbyiest based test kit for nitrate Salifert is probably the best.

 

[ccLansman]

thank you for the response jdowns, i have had the test kit for a long time and that may be the case, i normally shake it well but never hit it on any surfaces as the damn stuff is really thick. Ill give it a go when i get home.

 

[ccLansman]

bad news, i hit the bottle a few times and shook the heck out of it and it returned with 80ppm ... so i did a 50% water change. I guess back to the drawing board. I still cant get my plants to have explosive growth. I have insane pearling after a water change and decent normally. Should i up my co2 injection?

 

[SuperColey1]

I took this info from another forum that asked the following companies the shelf life question so maybe useful in reference to this thread. these are the figures that the actual companies returned so they may be true or they may be a little ambitious. Who knows but its a start:

Aquarium Pharmaceuticals:
Test Solutions Shelf Life from bottling date
Wide Range pH Test Solution 3 years
Ammonia Test Solution #1 3 years
Ammonia Test Solution #2 3 years
High Range pH Indicator Solution (m-Cresol Purple) 3 years
Nitrate Test Solution #1 3 years
Nitrate Test Solution #2 3 years
GH Test Solution 3 years
KH Test Solution 4 years
Nitrite Test Solution 4 years
Fresh Water Ammonia Test Solution (Nessler) 5 years
Fresh Water pH Indicator Solution 5 years
High Range pH Indicator Solution (Cresol Red) 5 years
Salt Level Test Solution #1 5 years
Salt Level Test Solution #2 5 years


To determine bottling date check the lot # on the reagent bottle. The last 4 digits are the month and year of bottling.

Example: 33A1201 would = a bottling date of December 2001.




Hagen:

All of our test kits have a shelf life of four years. Each package is marked with an expiration date. Please reply if you have any further questions.




Tetra:

The kits have a five-year shelf life. Once you open them you should discard them after a year.

I would assume that as most of these kits will use the same ingredients that as AP states different shelf lives that the other 2 are giving a 'answer and get rid' statement rather than the actual facts!!!

Hope this helps
AC

 

[JDowns]

bad news, i hit the bottle a few times and shook the heck out of it and it returned with 80ppm ... so i did a 50% water change. I guess back to the drawing board. I still cant get my plants to have explosive growth. I have insane pearling after a water change and decent normally. Should i up my co2 injection?

Ask yourself why this might happen now.

You have a liquid solution with two parts internally. Is that reagent dependant on a thorough mixing during each use. So if you don't mix well enough each time is the solution out of balance (the two parts are no longer in balace). This would make sense to me, if this is incase problematic, not 100% sure on the importance of the two parts having to be perfectly mixed each use. If this is the case. It would only take one bad shaking of the reagent and from then on the bottle is a waste.


If your dosing EI and have decent light (which it appears you do), I would suspect CO2 is your problem. Is the filter clean? How is your circulation. I can tell you from my own personal battles 9 times out of 10 its turned out to be CO2.

I've found that adding more CO2 with added surface agitation (O2) has really improved things for myself. Often I think we get in a thought process that to get better CO2 we should limit outgassing. When we should be improving O2 while adding CO2.

Maybe Tom can chime in on if the bacteria are O2 sensitive to the point that by adding more CO2 without adequate O2 they fail to thrive, and what that relationship might be.

 

[SuperColey1]

After water changes that isn't plants pearling!!! After water changes you are putting lots of O into the tank and it naturally gets trapped under leaves. Most tanks have unbelievable amounts of bubbles after water changes.

AC

 

[Tom Barr]

I think some of the NO3, particularly in older tanks, denitrification. If you add enough KNO3 over time, the bacteria will build up and the sediment acts a denitifying sand filter...........popular in reef tanks.

I routinely deep vacuum or pull up roots etc to prevent it as much.
I'm not sure how much is being removed as N2 gas though from bacteria.

Might be a lot, might be very little.
Would depend on the tank, sediment characters etc.

I do not know.

I had a decent test set up to look at it, but never followed up on it
I think ti was something where we add the KNO3 and plants, no fish etc, run the tank, measure the uptake over 2-3 months in an established tank.
Remove the plants(yes, this has a large effect on the denitifying bacteria) and the roots(or I could snip the tops off and leave the roots- they will rot and reduce the Redox levels- causing issues with the bacteria as well over time).

I think I'd have to measure the Redox along with this, or I could use the N2O and acetlylene method to really be aggressive(yes, I'm afraid so, better than the above method/s). I think more than 4-5ppm per day of uptake for plants is reasonable and high. More than that, likely something else is going on.

Kit issues, you can also add the KNO3 at a known dose(say add 10ppm), wait about 30 min, then measure the NO3 before and after you dose.
If you do not get ~10ppm difference, something's up.

Regards,
Tom Barr