Nitrate dosing...aka aquatic science-ish experiment

klwheat

New member
Ok, some quick background to start.
My 90 gallon reef has been going strong for a couple of years. The majority of my corals have grown like crazy, and I love the tank. (In fact, planning a big upgrade soon😄).
However, I have a few corals that just haven't seemed happy. A couple of sps that are showing not great color, poor PE, and my elegance has just never been happy.
Well, I like to read...a lot. So, I've been doing a bunch of research. I hadn't really heard of the term ULNS (ultra low nutrient system) before, but it seems my tank fits that definition. I was concerned that my test kits may have gotten old, because these corals weren't happy, but my parameters are always exactly where I was trying to keep them. Nitrates 0, phos 0, calcium 400-450, alk 7.5-8, mag 1300-1400.
I've occasionally had small algae issues, put some gfo in a reactor, and ended up with cyano instead until I pulled it out. Also, with gfo (always less than 1/2 the recommended amount) my corals did NOT look happy.
So, the more I read (some articles by very reputable sources) the more I discover that perhaps my nitrates are, in fact, too low. I didn't know that was possible, I always thought 0 was the goal.
So, I decided to try to raise my nitrates from 0 to 2-5ppm. I increased my feedings significantly as well as increasing my dosing of amino acids, phyto and coral food (reef roids and reef chili are the ones I've used).
I haven't had any luck increasing my nitrates...but my phos managed to go from 0-0.02 up to 0.16. Enter cyano 😞
Turns out, the bacteria in my system are excellent at processing nitrate, but significantly less efficient at getting rid of phos (yes, I understand why now...lol).
So...how do I increase my nitrates some without increasing phos at the same time.
Enter nitrate dosing (something I NEVER thought I'd do).
Well, here's how my evening went.
Test nitrates - 0 (no surprise)
Dissolve 2tbsp potassium nitrate in 2 cups of water.
Add 10ml nitrate solution.
Recheck nitrate after 1 hour -0 (dang, was hoping for something!)
Add 10ml nitrate solution
Recheck after another hour - still 0
(Seriously?!)
Add 20ml nitrate solution
Recheck after 1 hour - 1ppm!
Finally! I managed to have detectable nitrate in my tank.
So, what does this mean...well, anecdotally, a couple of my sps have more PE than they've had in weeks or longer.
Is this actually attributable to the increased nitrate? Not sure yet. However, the experiment will continue.
I'll keep everyone informed with my testing and results!
 

mcgyvr

New member
Good luck.. Should work out well for you it seems..

Just like plants..Corals need fertilizer too..
No N-P-K in the dirt.. Poor plant growth.. Too much N-P-K and you hurt the plants.. Just the right amount and voila..
 

klwheat

New member
Ok, tested again this morning...0.75ppm. So, just dosed another 15ml. Will recheck in a while.


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klwheat

New member
Good luck.. Should work out well for you it seems..

Just like plants..Corals need fertilizer too..
No N-P-K in the dirt.. Poor plant growth.. Too much N-P-K and you hurt the plants.. Just the right amount and voila..



Thanks! That's what I'm hoping for!


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Narzyzz12

Member
I've been adding the KNO3(2mL/day) to my sps dominate nano(8gallons) for about 6 weeks so far colors have improved a bit and they seem to be encrusting faster too
 

klwheat

New member
Nitrate dosing...aka aquatic science-ish experiment

Good to hear Narzy. I'll keep updating as mine progresses too.


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twf0369

New member
Dosing NO3

Dosing NO3

Keep us posted. I too just started dosing tonight. I have about 160 gallons of water, being conservative, and used the same mixture as you. 2Tbsp of Stump remover and 2 cups of RODI water.

Thanks.
 

klwheat

New member
Haven't tested mine in the last 2 days because I was out of town. Will try to do so tomorrow. One thing to note though, I have better PE on a couple or corals than I've had in a WHILE.


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twf0369

New member
Which test kit are you using during this process? I am using Red Sea and I got up to 1ppm. Like you, I want to take this slow because I've never really read any NO3 in my tank. I'll go at it again tomorrow.
 

klwheat

New member
I'm using the stump remover as well. I'll test when I get home from work tonight and update again.


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tmz

ReefKeeping Mag staff
Premium Member
There are three outcomes I look for when I tweak tweak my system with nitrate:

1) PO4 reduction; a nitrogen deficiency can limit organisms that take up phosphate; likewise a phosphate deficiency can limit nitrogen uptake. They need both as well as other nutrients;whichever nutrient is deficient will be limiting ;see Liebigs law of the minimum.

2)Coral vibrancy in case they are stressed by a nitrogen deficiency;

3)Nuisance algae growth which can occur with extra nitrogen sourcing.

FWIW, I dose a very small amount of sodium nitrate every other week or so (1tsp for 650 gallons) ;this usually brings the system to around .5 to 1ppm NO3 which works well. NSW is around 0.2ppm ; I think shooting for 5ppm is a bit high particularly with 0 PO4 readings. I use sodium nitrate vs potassium nitrate to avoid potassium buildups over time.

BTW, what methods are in play to keep NO3 and PO4 at zeros: phospahte binders, carbon dosing ?
 
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klwheat

New member
FWIW, I dose a very small amount of sodium nitrate every other week or so (1tsp for 650 gallons) ;this usually brings the system to around .5 to 1ppm NO3 which works well. NSW is around 0.2ppm ; I think shooting for 5ppm is a bit high particularly with 0 PO4 readings. I use sodium nitrate vs potassium nitrate to avoid potassium buildups over time.

BTW, what methods are in play to keep NO3 and PO4 at zeros: phospahte binders, carbon dosing ?

The only methods I've used thus far to keep NO3 and PO4 at zero is live rock, well stocked fuge, and big skimmer. I'm going to be aiming for about 2ppm NO3 (I agree, 5 may be high given that I've been at 0 for quite some time).
With the sodium nitrate, what are you using (and where do you get it)? Has it impacted your salinity at all? Also, is that 1tsp powder/granule or diluted?)
 

tmz

ReefKeeping Mag staff
Premium Member
I use this:

https://www.dudadiesel.com/search.php?query="sodium+nitrate"

Sodium is present at 10.500ppm in salt water. The addition of sodium nitrate to get 1pmm of NO3 is infinitesimally small without any discernible effect on salinity.

I dissolve 1 tsp of granules in about a half liter of ro/di water and add it to a high flow area of the sump. Again that's for 650 gallons in my case.
 

klwheat

New member
OK, update time. So, I haven't added any potassium nitrate since 8 December. My nitrate levels are holding steady between 1 and 2 (not quite either color) with the Red Sea kit. Interestingly (and opposite what I expected), my phosphate has increased from 0.03 to 0.30 over the last 9 days. I have not increased feedings or anything else that I can think would account for this. Other parameters are stable. Salinity 35ppt, alk 7.5, calcium 450, mag 1350. Perhaps I'll do a water change and check again in a day or 2. For now, watching and testing.
 
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klwheat

New member
actually...now that I think of it again, I did have a change in my tank. My flow in the 90 is from the return pump, an MP40 and an MP10. However, a few days ago, my MP10 decided to quit working. Perhaps this decrease in flow has caused an issue?
 

kenith

New member
The problem I've read about stump remover is how pure the potassium nitrate is, though it's suggested the purity is 99%. I've been trying to find a reagent grade. So far no luck yet
 
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