Can I reduce nitrates without reducing phosphates?

nim6us

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I just got done with a horrible bout of dinos and the lesson I learned was it’s bad to run at 0 phosphates and 0 nitrates as your goal.

While I understand now I need some of each I feel my nitrates are too high 25ppm. While my phosphates are just barely detectable using the Hanna ULR Checker at .055ppm.

The quandary I’m left with is how do I bring those nitrates down without zeroing out my phosphates?

My current idea was to use NoPoX, which bring them both down and then dose phosphates to keep some in the water. I don’t know if that’s crazy or there’s a better solution... hence this post.
 

Auquanut

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Your NO3 and PO4 are not that bad in my opinion. I had nitrates well over 25 for a long time with low phosphate (no visible problem in the tank). When my fuge really started taking off, the nitrates fell without really affecting the phosphate too much. I personally would try water change and reduced feeding before I resorted to dosing. Just a thought. Whatever you do, take one step at a time and go slow.
 
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nim6us

nim6us

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@Auquanut

I do have a macroalgae reactor that I took offline to deal with the dino outbreak. I was planning on bringing it back online but was worried it'd zap my phosphates to nothing. That may be the more holistic approach. Fire up the fuge and let it deal with the nitrates, if the phos dips to low I can always dose phos.

I guess my concern was the nitrates being so high. I had read you really only wanted about 2-5pmm so when I saw it jump to 25ppm I was looking for a quick fix. However if 25ppm is not an alarm level of nitrates, then that changes my game plan.

Thanks for the advice ;)
 

Jet915

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My phosphate runs around 0.1 and my nitrates are around 30 and my corals grow well.
 

cedwards04

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I shoot for 5-10ppm nitrates and 0.03-0.06 phosphates. That being said, I wouldn't be super concerned over your nitrate levels provided everything is looking good in the tank.

You mentioned nitrates shot up. What were you doing or changing that moved your nitrates from 0 to 25? There's a fair chance the nitrates will come down on their own with time. Phosphates will only come down provided there is bacteria feeding on them, or algae is consuming them faster than you are putting them in. I think I'd give it some time and see what happens.
 
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nim6us

nim6us

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Good to hear it echoed again that 25ppm isn’t that much to be concerned about.

As for the rise, it wasn’t really an overnight issue. I’ve been battling dinos for about 2 months.. had them for close to 4 months but only really started fighting them for 2. I naively thought they would work themselves out. Anyway, when I started all my methods the #1 piece of advice I read was to stop water changes, that it’s like throwing gas on a fire. Nitrates crept up to about 5ppm just stopping that. But the big increase was when I started with DinoX, 10 doses over 20 days. I took out my algae reactor and carbon.

I guess it’s like anything in reefing, the problem didn’t happen overnight and I shouldn’t expect a solution overnight either.
 

Auquanut

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I guess it’s like anything in reefing, the problem didn’t happen overnight and I shouldn’t expect a solution overnight either.

Truer words have never been spoken my friend.
 

Randy Holmes-Farley

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If you want to reduce nitrate and not phosphate, the two best methods are organic carbon dosing and water changes, but neither is perfect in that they both lower phosphate some, just not nearly as much as nitrate.
 

cedwards04

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Waterchanges would lower phosphates and nitrates the same, wouldn't it? A 20% waterchange is going to lower both by 20%. Unless there are phosphates in the new water.
 

Randy Holmes-Farley

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Waterchanges would lower phosphates and nitrates the same, wouldn't it? A 20% waterchange is going to lower both by 20%. Unless there are phosphates in the new water.

You might think so, but no. Far more phosphate is bound to rock and sand than is actually in the water. If you do a 100% water change, some of this bound phosphate comes off and re-equilibrates with the bulk water, bringing the level back much of the way up to the original value. Thus the rock and sand act as a strong buffer against phosphate changes, reducing the jump up on addition and reducing the drop down on removal.
 

bar|none

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You might think so, but no. Far more phosphate is bound to rock and sand than is actually in the water. If you do a 100% water change, some of this bound phosphate comes off and re-equilibrates with the bulk water, bringing the level back much of the way up to the original value. Thus the rock and sand act as a strong buffer against phosphate changes, reducing the jump up on addition and reducing the drop down on removal.

That is a really interesting tidbit. Thank you.
 

Lerequin

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Hi @nim6us how did you stabilise your NO3 in the end? I have the same situation where NO3 is rising more than PO4. According to this article, PO4 can be the limiting factor for chaeto growth. I wonder if dosing PO4 would help the macro refugium soak the NO3…
 
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nim6us

nim6us

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Wow what a blast from the past! I’ve learned so much more since then. Nowadays I’m actually dosing nitrate to bring it up. :p

That said my tool for nitrate removal is my chaeto reactor. I usually run it at 8 hours a night but I will turn it up to 12 or even 15 hours to bring it down. Otherwise if I have something sudden happen I’ll do a few big water changes.

I did previously use NoPOx and it works but I was too aggressive and got cyano. So if you do go that route test your phos and nitrate weekly, maybe even twice a weekly.
 

Lerequin

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Thanks. Since my post I realised there was salt creep obstructing the skimmer's air intake. After cleaning the skimmer, everything is back to normal: 25 to 5ppm NO3, 0.08 to 0.04ppm PO4. This confirms the skimmer is a great nitrate remover.
 

Islandvib3s

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You might think so, but no. Far more phosphate is bound to rock and sand than is actually in the water. If you do a 100% water change, some of this bound phosphate comes off and re-equilibrates with the bulk water, bringing the level back much of the way up to the original value. Thus the rock and sand act as a strong buffer against phosphate changes, reducing the jump up on addition and reducing the drop down on removal.
Do you think if I removed my sand bed and went BB it would reduce my nitrates and phosphates in general?
 

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