# Test kit comparisons



## BryceM (Nov 6, 2005)

I took the plunge and ordered the Lamotte kits. I had previously been using the Nutrafin / Hagen kits for NO3 and PO4.

I use EI dosing and had been gradually increasing my fert regime. I was recently adding this to a 46 gallon:

KNO3 - 1.5 tsp / week (32 ppm / week - dosed on M/W/F/Sat)
Fleets - 6.8 ml / week (6 ppm / week - dosed with KNO3)
Flourish - 40 ml / week (1/ml/gallon/week - dosed on T/T/Sun)
Equilibrium - 2 tsp @ WC time (50% WC/week)

My journal shows consistent NO3 readings in the 20 range (per Hagen)
My journal shows consistent PO4 readings in the 2-5 range (per Hagen)

Lo and behold, the Lamotte NO3 kit reads around 70 ppm NO3 and 4 ppm PO4. I had a tetra die recently, green dust algae is taking over, and plant growth seems slower than previously. The fish did not appear well at all - very sluggish, angel hiding all the time, congos sitting near the bottom, not eating well, etc. I did a large WC, NO2 now ~20 ppm and PO4 now 2 ppm. The fish are MUCH happier. They actually swim around again now. I'm hoping the plants outgrow the green dust stuff everywhere. I had been backing off my CO2 assuming that this was the cause of the fish distress. This certainly helped my algae farm.

Net result - well documented poor decision making based on bad assumptions from hobby-grade test kits. In their defense, the PO4 kit seemed accurate. You've gotta love Lamotte. I only wish I'd ordered the Lamotte KH kit too (its only $15 or 18 more).

I still think the EI method is generally foolproof in the long run, but you need some idea of how 'hot' to run the dosing and an accurate idea of what comes out of the tap. In my case I seemed to be dosing too much for the 50% weekly WC to keep me out of trouble.

Hope this helps someone out there.


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## Bert H (Mar 2, 2004)

Good post guaiac. Had you ever run a standard (known concentration) with your 'hobby grade' kits to determine their accuracy? I recommend you run one with the Lamottes as well, if you haven't. For the amount of time it takes, it's well worth it to verify the accuracy of whatever test you run.


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## summitwynds (Jun 3, 2005)

Where did you buy your Lamotte kits? 

I stopped testing the day I got my new Hagen kit a couple weeks ago. The very first test was for KH. I had consistently been getting a reading of 2 from my Tetra test, and the Hagen said I had a 9 KH. How can these cheap tests really be trustworthy?


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## MatPat (Mar 22, 2004)

Welcome to the world of LaMotte Guiac Boy 

I have only used a couple of brands of test kits in my planted tank days, but I would never go back to the hobbyist grade kits...kind of like going back to DIY CO2 after using pressurized! Once I got my LaMotte kits and founf how easy they were to use, I tossed my other kits!

I love the ease of use of these kits and once you make the initial purchase of the kit with the comparator, the refills are about the same as other test kits. It is so nice having a vial of colored water to compare your sample too. I could never match the color on those printed white charts with a sample of water.

I once used one of my hobbyist grade kits to test the water with my wife and a friend. We all saw 3 different levels of NO3 but everyone had the same level with the LaMotte.

Here are a few online sources for LaMotte kits:
http://aquaticeco.com/

http://www.marinedepot.com/homepage.asp - They accept PayPal 

http://www.lamotte.com/ While you can't order from them online, they will be more than happy to let you order over the phone


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## BryceM (Nov 6, 2005)

I got mine from marinedepot. Their kit prices are pretty good, but after shipping its probably about the same as anywhere else. Don't think I'll ever use anything else. Anybody know the best source for refils?


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## Raul-7 (Feb 4, 2004)

With all that speculation over the accuracy of the CO2 chart, I'm surprised you didn't order a CO2 test kit. 

IMO, I like Salifert better; it's a high accuracy test kit without the high accuracy price tag (depends on where you buy it from). The only problem is they still haven't shipped their gH and CO2 test kits to the US yet.

http://www.aquaticeco.com/index.cfm/fuseaction/listings.categories/ssid/13 has the best prices on refills.


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## BryceM (Nov 6, 2005)

I'm sure that I'll eventually end up with the CO2 and KH kits too, but I wanted to get a handle on my ferts first. The CO2 chart accuracy question turns out to be much more complex than I first thought. I'll post my recent findings on my other thread. Thx for the info on refills.


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## HeyPK (Jan 23, 2004)

One thing to keep in mind about the LaMotte CO2 test kit, or any CO2 test kit that titrates a sample with a dilute NaOH solution and uses phtholphthalein as the color indicator: The end point where the phenolphthalein begins to turn pink is an arbitrary end point. All it means is that you have raised the pH up to around 8. It does not mean that there is 0 ppm of CO2 as far as the plants are concerned. Plants that can utilize the bicarbonate iron as a CO2 source can still get CO2 until the pH gets up to around 10 to 11! Even plants that can not utilize the bicarbonate ion can get the pH up to around 9. Keep in mind that somewhere along the CO2 availability range, the plant will become CO2 limited, meaning that the availability of CO2 is limiting growth rate. Just where the plant becomes CO2 limited depends on the species. Thin, finely divided plants with a large amount of surface area and the ability to utilize bicarbonate, such as Najas, may not be CO2 limited until the pH is around 9. Thick plants with much less surface area, such as Anubias, may be CO2 limited unless the test kit indicates 20-30 ppm CO2 and the pH is around 6.5. In general, plants which are capable of emersed growth, but can adapt to submersed growth require higher levels of CO2 than plants which can only grow submersed.


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## Raul-7 (Feb 4, 2004)

Basically, the test kit can't detect CO2 at a pH above 8? 

About the refills, why does the site offer both replacement reagents and refills; yet their prices differ? Is replacement not the same as refill?


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## HeyPK (Jan 23, 2004)

Right. when the solution begins to turn pink, the titration is over. You count the number of drops of NaOH solution you added and figure the ppm of CO2. There is still more CO2 than that that is available for plants, although they might not be able to get very much of it very fast.


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## dennis (Mar 1, 2004)

So, could one buy the ragent refills for roughly half the price and use your own test tubes, pipets, etc? I probably have enough lab equipment sitting around....... Course, one would have to get a copy of the directions from someone else


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## BryceM (Nov 6, 2005)

I guess, but what you really need is the 'octet comparator' thing with 8 pre-filled glass vials set in a plastic holder that you use to compare your sample to. They are MUCH easier to distinguish than the vague, partly faded, printout that has 8 shades of pink that all look the same to me.

I think this is 90% of the secret about why Lamotte is so much better. The other 10% is probably the cool case it comes in . I suspect their quality control about what actually makes it into the reagent bottles is probably better too, since the vast majority of their market is people who actually use these things for real (not hobby) applications.


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## plantbrain (Jan 23, 2004)

FYI, Lamotte is great for hobbyist.

But...........at these high upper ranges, the accuracy goes way down unlessd the test kits are specific for the ranges.

Most Lamotte kits are good at the 0-30ppm range.
Some are broad ranged, but then they are problematic with narrow accuracy.

I use 0-30ppm NO3 ranged test kits and then have a broad ranged one that goes to 100ppm.

Similar things exists for Fe, PO4 etc

I've had 75ppm for 3 weeks without issues, you can tell what the fish are looking like and the response to high NO3 by doing a guppy test in a container.

Shrimp die first in every case with high NO3 from KNO3 from everything I've seen.

You can estimate the max NO3 based on a math series to find the max NO3 build up over time with a 50% water change per dosing peroid(a week).

So 64ppm(you add 32ppm per week) is the max level, so at ~ 70ppm, you woukld also neecd to assuem no uptake from the plants over the week also.

So the test kit might be out of range.

The dosed levels cannot be higher than 64ppm.
You can also dose the same and do larger water changes, which will lower the levels as well.

20-30ppm is a good target overall for NO3.
Try 20ppm a week, if things get to 40ppm(again, that assumes no uptake by plants all week long, I'd expect 7-20ppm uptake for a week), then you can back off and observe, or you can make some standards to see the range of interest and the test kit's accuracy.

Make at least 3 known standards if you want to do this.

Regards, 
Tom Barr

www.BarrReport.com


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## HeyPK (Jan 23, 2004)

You can even mix up your own reagents quite cheaply if you have access to a chemical stockroom. Sodium hydroxide comes in little pea-shaped pellets, and you can weigh one and figure out how much water to add to make a 0.01 molar solution. You will get somewhere over 100 ml, enough to last a long time. A small amount of phenophthalein powder can be dissolved in ethyl alcohol and then diluted 50% with water. Keep the bottle of NaOH solution tightly stoppered to keep CO2 in the atmosphere from reacting with it. The best acid to use is potassium acid phthalate, because it comes as a solid, and can be accurately weighed out. Acids like Concentrated HCl are not accurately made up, and so you don't have a good idea what the exact concentration is. 

Suppose you test your tank water and find that it is way over the endpoint--It is very pink. You can back-titrate with .01 molar acid to the end point, where there is just a trace of pink. The number of drops of the .01 molar acid are equivalent to the number of drops of the .01 molar NaOH.


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## BryceM (Nov 6, 2005)

Thx Tom.

I'm wondering if I'm really putting in what I think. My KNO3 is in a finely powdered form and I've been measuring it dry by teaspoons. I think most people dose it in pellet form. An accurate electronic scale is also in the works someday. It's possible that more was going in than I thought. For the same reason it is hard to mix up a precise 'known' solution. Maybe I'll get some of my lab friends to help me out with this. I could get pretty close using the teaspoon thing, but if I'm going to make a 'standard' solution I want it to be precise. As for now, there are still too many unknowns to pinpoint exactly why things got like they did. Maybe my estimated WC's are only 40%, etc, etc. I'm sure the fish are contributing a bit of nitrate to the mix too - this is a pretty heavily stocked tank.

I don't think the nitrates being in the 70's was the worst thing in the world - I only lost one neon (maybe it would have croaked anyway), but noticing some ill effect in my fish while believing my NO3 to be just fine (20-30 ppm) caused me to back off on my CO2 (which I had been increasing gradually). The combination of the two certainly helped out my algae. In any case the fish do look MUCH happier now.

My Lamotte kit measures N from 0.25 to 10, multiplying by 4.4 to convert to NO3 = a range of roughly 1 to 44 ppm. For my test sample, I added 30cc of distilled water to 30cc of tank water using a 60cc syringe. I then multiplied my 'answer' by 2. I think this is a pretty reasonable way to stay in the valid range of the kit.

I'll keep posting with what happens to the measured NO3 levels. After another 50% WC on 12/31 my NO3 read 22 ppm with PO4 of 1.4. I added 1 ppm PO4 and 5 ppm NO3 and will check levels again tomorrow. I'm hoping to see NO3 levels in the 20 range.

I absolutely agree that there is significant NO3 uptake occurring - I get great pearling and I'm cutting many of the plants in half on an almost weekly basis, but something allowed my NO3 to get much higher than I thought it would.


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## dennis (Mar 1, 2004)

plantbrain said:


> 20-30ppm is a good target overall for NO3.
> Try 20ppm a week, if things get to 40ppm(again, that assumes no uptake by plants all week long, I'd expect 7-20ppm uptake for a week),


Some questions:

So 20mg/l would be the max uptake of a fully planted aquarium running under non-limiting conditions?
How much impact does plant mass have on this? Also, is there a good way to measure plant mass in an aquarium?
Would this be a constant uptake rate(given non-limiting conditions) or would the rate taper off some as the plants filled their reserve stores?


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## BryceM (Nov 6, 2005)

I think these are very hard questions to answer. With sensitive enough equipment you could measure uptake it in a given tank, with a given plant mass, on a given day, under given lighting, with other given nutrients in the tank. You could probably do it a few hundred times on lots of different setups and get a pretty good 'gut' feel for exactly what the plants need.

Short of having that kind of experience, I think you need some fairly frequent, reasonably accurate checks of NO3, PO4, pH, and KH to get an idea of how much you need to dose. Once you know what a certain tank is going to use, much less frequent testing would be needed just to make sure it doesn't wander out of the 'sweet spot'.

Going back and reading this post it's amazing to me how quickly things turned around. I haven't had any algae problems to speak of since getting the CO2 squared away and having some good NO3 and PO4 numbers to base ferts on. By far the biggest problem now is keeping the stems trimmed back enough to let some light down to the forest floor.


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## MatPat (Mar 22, 2004)

guaiac_boy said:


> I absolutely agree that there is significant NO3 uptake occurring - I get great pearling and I'm cutting many of the plants in half on an almost weekly basis, but something allowed my NO3 to get much higher than I thought it would.





guaiac_boy said:


> By far the biggest problem now is keeping the stems trimmed back enough to let some light down to the forest floor.


These two things sound like maybe in the past you were adding a good amount of NO3 but the CO2 was a bit low, limiting both plant growth and NO3 uptake.


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## Edward (May 25, 2004)

Hi all,

May I rename this thread to *EI Technical Discussion Thread*?
.
.
.


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## John S (Jan 18, 2005)

I've had 75ppm for 3 weeks without issues, you can tell what the fish are looking like and the response to high NO3 by doing a guppy test in a container tom what do the guppys do die or swim weird????


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## BryceM (Nov 6, 2005)

Edward said:


> Hi all,
> 
> May I rename this thread to *EI Technical Discussion Thread*?
> .
> .


Ya, since that's where it's going.........


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## Edward (May 25, 2004)

Edward said:


> Hi all,
> 
> May I rename this thread to *EI Technical Discussion Thread*?
> .
> .





guaiac_boy said:


> Ya, since that's where it's going.........


I was more thinking about dead fish, uncontrolled overdosing and need for very expensive test kits.


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