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N and P dosing

In the other thread I stated that meeting other hobbyists was the best thing I'd ever done to my reef, but honestly dosing KNO3 might actually be the best thing. I'd always had zero (on a Red Sea low range kit) nitrate, but must have been just barely below the edge. As my big tank matured I started having issues with pale coral, STN on dinner plate sized colonies, etc. I had stable alk, I had more phosphate than I wanted, I tried iodine, dips, all sorts of things. Some stuff did great, but every now and then a colony would RTN. I had a dense softball sized acro colony that I grew from a 1/8" speck of a frag in perhaps 8 months RTN in 2 days. At the same time a nearby frag of the same coral was untouched.

Then I started dosing KNO3. It worked out to about 1 PPM/day in a 600 gallon system. Overnight all of my RTN issues stopped. My STN issues stopped. Acros got their color back. Mystic monty grew like a weed, the acros became the fast growing fuzzy sticks we see in magazines, unicorns and kittens pranced in the dreams of all who came by. Oh, and the algae that was pretty bad beforehand really took off too. I didn't have to dose phosphate because even with nearly no feeding it stayed higher than I wanted (leaching out of something).

My current tank until recently I was dosing nitrate and phosphate, but as I've started to kill the algae off my need to dose has greatly decreased.

I'm a sometimes planted tank guy, so I get mine as dry powders from GLA, mix it as I see fit, and dose until it becomes stable at my target value.
 
I make my own. Same stuff that you tuber reefofhex uses. If you like I can make you some. I got both phos and nit

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Mike Yasin said:
After an hour you read 0. Which Hanna the phosphate or phosphorous?


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I ask because if you’re using the Phosphate ULR is +/- 0.04ppm, so technically you’re within its margin of error assuming your reagent is not expired.

the Phosphorus ULR is +\- 5ppb, or .005ppm accuracy

I would not add anymore unless you have confidence in your testing equipment. Maybe try diluting your mix in some volume of RO or tank water and test?
 
Mike Yasin said:
I ask because if you’re using the Phosphate ULR is +/- 0.04ppm, so technically you’re within its margin of error assuming your reagent is not expired.

the Phosphorus ULR is +\- 5ppb, or .005ppm accuracy

I would not add anymore unless you have confidence in your testing equipment. Maybe try diluting your mix in some volume of RO or tank water and test?
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0.005 ppm phosphorus = 0.015 ppm phosphate. What I read says accuracy of phosphate checker is 0.02 ppm. So the same basically.

Plus I think the ULR phosphate and ULR phosphorus checkers/regents are exactly the same functionally, the phosphate just multiplies by 3 for you. So I really seriously doubt there is any differential in accuracy.
 
I’ve found phosphate gets sucked up extremely quickly for a little while when you first start dosing it. I accidentally did a 10x dose at one point and it was gone within a couple days. Once I’d been dosing for a bit this stopped being the case.
 
JVU said:
0.005 ppm phosphorus = 0.015 ppm phosphate for what it’s worth. What I read says accuracy of phosphate checker is 0.02 ppm. So the same basically.

Plus I think the ULR phosphate and ULR phosphorus checkers/regents are exactly the same functionally, the phosphate just multiplies by 3 for you. So I really seriously doubt there is any differential in accuracy.
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Per someone who wrote to Hanna on R2R the phosphorus ULR checker is slightly more accurate at low range than the phosphate ULR. This surprised me a bit as I thought the phosphate ULR was just doing the math (and had a longer time-out time), but I have no reason not to believe it.
 
For all we know the person they wrote to doesn’t understand how the molecular weight difference between phosphorus and phosphate affect the numbers. I’m almost completely sure they are the same unit just rebranded, slightly longer timeout because that was an issue, and multiplies by approx 3 for you, gives results in ppm vs ppb. Plus after doing the math, there is almost no difference between 15 ppb and 20 ppb, which is what we are talking about for accuracy difference.

The history of it is that for a long time there was only the phosphorus checker. They got tons of requests to just make the changes above and release it as a phosphate checker, but they resisted for years because they (the engineers) thought it was dumb to just rebrand the same product. But eventually they did release it and it’s more convenient for our use, so that‘s good. But not more accurate as far as I know. And if a customer support or sales type told me it was I still wouldn’t believe them personally since I know the backstory and how easily this gets confusing. Not that it makes a big difference anyway.
 
The 2 places the Redfield ratio, or at least the way it frames the conversation, are helpful are in how N, P, and C get used up in certain ratios, and to remind us that one of those is always approximately zero in every system with mature bacteria (because they keep growing until one is 0).

The first part is helpful because it tells you to expect about 10 times as much nitrate to be used up as phosphate. Dose 1 ppm of nitrate, and expect phosphate to go down about 0.1 ppm. That is useful info because otherwise you might wonder why the phosphate is hardly moving when you dose nitrate.

The second part is helpful because for whichever of these 3 is zeroed out, you will need to add more than you think until one of the other 2 zeroes out, which is relevant to @MarAquatic ’s issue above. Normally we don’t think about it this way because carbon is by far the most likely to be rate limiting (zeroed out) in our systems so we are used to having both nitrate and phosphate around. But if it isn’t then you get issues like this. That’s one reason why people say carbon dosing doesn’t work for them, if they are trying to reduce nitrate for example by dosing NOPOX but their phosphate goes to zero, it‘ll look like it isn’t doing anything because the nitrate doesn’t budge further.
 
JVU said:
0.005 ppm phosphorus = 0.015 ppm phosphate. What I read says accuracy of phosphate checker is 0.02 ppm. So the same basically.

Plus I think the ULR phosphate and ULR phosphorus checkers/regents are exactly the same functionally, the phosphate just multiplies by 3 for you. So I really seriously doubt there is any differential in accuracy.
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Whoa- I can’t believe I did that. Thanks for the quick work and correction.

I’ll have to go look at the data sheet- but did think the Phosphate checker is .04ppm


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Rostato said:
I started no3 dosing again. Got my algae under control
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I just started today. I bought some reagent grade Sodium Nitrate from Amazon and mixed 50g NaNO3 in 2L of RO/DI water. A 1ml dose should increase nitrates around 0.8ppm for 5 gallons of water.

My nitrates are always around 0.2-0.5. Gonna see if polyp extension and growth is better with nitrate dosing.
 
RandyC said:
I just started today. I bought some reagent grade Sodium Nitrate from Amazon and mixed 50g NaNO3 in 2L of RO/DI water. A 1ml dose should increase nitrates around 0.8ppm for 5 gallons of water.

My nitrates are always around 0.2-0.5. Gonna see if polyp extension and growth is better with nitrate dosing.
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Same for me. I’m always around .2-.5. I noticed much better polyp extension during my first try with it. But I didn’t reduce feedings. I’ve now reduced feedings and started back dosing.
 
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