Over 1 year in and still having parameter issues...

Randy Holmes-Farley

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Okay and what do you think about me increasing my dose or should I do the same dose for a few days?

Of nitrate? If you have confidence inn your kit, ramp it up fast until you have the amount you want 24 h later.
 

Randy Holmes-Farley

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So if I dosed 5mL of Nitrate and Phosphate and values didn’t change in 24 hours, should I double the dose? Also thank you for your input.

Yes
 

rhitee93

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Just another data point: I added 20ml of my 1M potassium nitrate solution yesterday evening and measured 1.7ppm of nitrates this morning.

That should have been about 3ppm worth, but it's been 30 years since I did any molar math.

My reasoning:
20ml of a 1 molar solution would be about 2g of KNO3. About 40% of that mass is potassium. I'm assuming the rest would dissolve into a "Nitrate" ion so that would be 1.2g. My system has 411,000 ml of water => (1.2/411,000)*1E6 = 2.9ppm.

I added another 20ml today and will report the test results tomorrow.
 
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rhitee93

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I measured the nitrates to be 3.6ppm this morning.

My NaNO3 Came in yesterday so I mixed up a 1M solution of it. (42.5g in 500ml of RODI water)

I dosed 20ml of this new solution which should be roughly equal to 3ppm in my system.

For the cost of a nitrate test each day, maybe I can quantify how much net consumption I am having over the next week or so.

The brown film that had formed when I got to zero nitrates is still largely there, but the areas where I scrubbed the rocks clean yesterday were still white this morning.
 
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CallMeLloyd

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Very nice, I'm still trying to figure this out. My last test showed 0.0 Nitrate & Phosphate. Somehow my Phosphate dropped 0.03 over night. Changed my dose and will test tonight and see what changes.
 

Randy Holmes-Farley

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Just another data point: I added 20ml of my 1M potassium nitrate solution yesterday evening and measured 1.7ppm of nitrates this morning.

That should have been about 3ppm worth, but it's been 30 years since I did any molar math.

My reasoning:
20ml of a 1 molar solution would be about 2g of KNO3. About 40% of that mass is potassium. I'm assuming the rest would dissolve into a "Nitrate" ion so that would be 1.2g. My system has 411,000 ml of water => (1.2/411,000)*1E6 = 2.9ppm.

I added another 20ml today and will report the test results tomorrow.

You can check nitrate dosing math using this calculator, but in the end, it's what's in the water that matters. :)

 

Randy Holmes-Farley

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Measured nitrates at 7.9ppm this morning. That's a bit more than I was expecting. We'll see what tomorrow brings...

FWIW, I would be wary of overinterpreting every change with kits that carry significant potential variability/error.
 

rhitee93

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FWIW, I would be wary of overinterpreting every change with kits that carry significant potential variability/error.
Yeah, after seeing the test result I was wondering what the Hanna test accuracy/precision is. I haven't looked it up.

My experimental errors should be pretty well controlled. I use a micro-pipette for measuring the sample, and generally have pretty good lab techniques.

I'm looking for the trend line in all of this, but don't have much time in the data yet.
 

Randy Holmes-Farley

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The Hanna HR nitrate, if that's what you use, claims +/- 2 ppm.

The LR is more complicated:

±0.25 ppm ±2% of reading @ 25 °C (77 °F)
±2.5 ppm ± 5% of calculated reading using dilution
 

rhitee93

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The Hanna HR nitrate, if that's what you use, claims +/- 2 ppm.

The LR is more complicated:

±0.25 ppm ±2% of reading @ 25 °C (77 °F)
±2.5 ppm ± 5% of calculated reading using dilution
Thanks, that is helpful. I'm using the high range kit, so there really is quite a bit of potential noise on top of my relatively low values.
 
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CallMeLloyd

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I dosed 24mL Neonitro & 3mL of Neophos last night. Will test again tonight when I get home but I am expecting the same results. How long or how much do I have to dose to get readable levels? The past couple days I've been getting what looks like brown algae starting to grow.
 

Randy Holmes-Farley

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I dosed 24mL Neonitro & 3mL of Neophos last night. Will test again tonight when I get home but I am expecting the same results. How long or how much do I have to dose to get readable levels? The past couple days I've been getting what looks like brown algae starting to grow.

The nitrate is only offsetting biological demand so can come up faster than phosphate which also binds to rock and sand as you add it.
 

rhitee93

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It is amazing how a few days of data start to make things more clear than they are when you are looking at just a couple of data points desperately trying to extrapolate what is going on.

This is a plot of the last week or so of my measured nitrates and what I would have projected them to be based on my dosing.

Nitrates 12-23.png


At first it felt like I was just feeding some hidden monster and waiting for it to explode in the tank. However, after plotting the error bars that Randy provided on the Hanna test kit, and giving it a few more days, it all started to make sense.

I'm glad I started dosing. The brown slime that started to form when my mitrates hit zero has pretty much gone away. Not sure what it was, but I'm hoping to see GHA grow again :)
 

Randy Holmes-Farley

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Is the projected nitrate value on, say Dec 6, just the total dosed from Nov 30 to dec 6, or are you subtracting out consumption somehow?

If it's just the total, then it's time to stop dosing because it suggests there is no ongoing demand for it.
 

rhitee93

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Is the projected nitrate value on, say Dec 6, just the total dosed from Nov 30 to dec 6, or are you subtracting out consumption somehow?

If it's just the total, then it's time to stop dosing because it suggests there is no ongoing demand for it.
The projection is just simple addition. I had no idea what the consumption really was. The plot was actually and attempt to understand it.

Thanks for the advice. My plan was to stop dosing today and to see how fast the nitrates fall. It's comforting to know you feel the same.
 

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