Nutrient Control

[RBU1]

What has everyone found to be the best for nutrient control? I have a 260 gallon tank. I have a refugium an algae scrubber and I run GFO. Still have what I believe to be cyano growing on some of the rocks both green and red. My phosphates read around .04. Nitrates around 20. Can't put my finger on the source of the cyano. My lighting is hydra 52hd lights. I'm thinking about trying something else like bio pellets. Not sure. Any suggestions?


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[ryeguyy84]

How old is the tank? Usually the scrubber will outcompete the fuge (assuming chaeto)

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[RBU1]

This tank has been set up since April. I transferred everything over from a 150 that was up for over a year. I have feather caulerpa in the refugium. The scrubber and refugium both grow algae.


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[nereefpat]

For me it's a mature tank with mature live rock. My water tests show very low N and P without ever running any GFO or carbon dosing.

Cyano growth is difficult to determine cause. We don't always know the cause. It isn't always nutrient related either. Flow is another factor.

 

[mcgyvr]

Bacteria seems to be the best nutrient control..
And carbon dosing to "supercharge" that bacteria..

After that ATS/macroalgaes seem to be able to process a decent amount..

One will basically never put their finger on the source of Cyano for me is a seasonal thing only coming in the early fall/winter (so right now mine is flaring up)..

Your nitrate levels IMO say that your ATS/Macros could be doing better or are undersized.. Simple liquid carbon dosing (cheap vinegar is all you need) could easily knock them down to nothing in a few weeks or so..

 

[RBU1]

Ok. Thanks. So vinegar dose on top of what I'm currently doing.


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[nereefpat]

I'm not a carbon dosing (vinegar or otherwise) expert...

But there may be an issue with stripping the PO4 with GFO, and then trying to lower the nitrates with vinegar dosing. You may want to pull the GFO offline...something to think about if you start carbon dosing and the nitrates don't drop.

 

[hotdrop]

I don’t think cyno is a nutrient problem. Isn’t it linked to silicate?

 

[mcgyvr]

I don't think cyno is a nutrient problem. Isn't it linked to silicate?

No that would be diatoms.. Diatoms feed off silicates..

 

[mcgyvr]

I'm not a carbon dosing (vinegar or otherwise) expert...

But there may be an issue with stripping the PO4 with GFO, and then trying to lower the nitrates with vinegar dosing. You may want to pull the GFO offline...something to think about if you start carbon dosing and the nitrates don't drop.

Carbon dosing doesn't seem to effect phosphate levels nearly as much as it does nitrates..
If they have a real phosphate problem (phosphate levels would rise out of control without running GFO) then they can continue to use it while carbon dosing..
If you find phosphates are dropping too quickly then discontinue its use temporarily or permanently..

 

[RBU1]

Ok. Thanks. Think I'll try pulling the GFO and dose a carbon source. Need to get a doser. Thanks.


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[nereefpat]

Carbon dosing doesn't seem to effect phosphate levels nearly as much as it does nitrates..
If they have a real phosphate problem (phosphate levels would rise out of control without running GFO) then they can continue to use it while carbon dosing..
If you find phosphates are dropping too quickly then discontinue its use temporarily or permanently..

If phosphates are near zero, will nitrates drop via carbon dosing?

 

[mcgyvr]

If phosphates are near zero, will nitrates drop via carbon dosing?

In my experience absolutely.. Ive never had elevated phosphate issues (never over .04-.06 ppm) and carbon dosing has always solved my nitrate issues..

Some have stated that one could be phosphate limited but I'm not really a big believer in that theory..

 

[nereefpat]

:thumbsup:

Phosphate possibly needs to be lower than 0.04 to be limiting then

 

[Uncle99]

In my experience absolutely.. Ive never had elevated phosphate issues (never over .04-.06 ppm) and carbon dosing has always solved my nitrate issues..

Some have stated that one could be phosphate limited but I'm not really a big believer in that theory..

I agree, I have been carbon dosing for more than 2 years now in order to maintain a constant 5ppm nitrate level. Does little if anything to phosphate likely because the amount of phosphate we are generally talking about is barely detectable.

 

[reefgeezer]

Cyano may not need inorganic N or P to grow. It can use organic compounds. IME, it occurs when dissolved organics are elevated to a point that they aren't being used by the other organisms in the system. Do you have a skimmer, run GAC, or employ anything that would limit DOC?

 

[RBU1]

Cyano may not need inorganic N or P to grow. It can use organic compounds. IME, it occurs when dissolved organics are elevated to a point that they aren't being used by the other organisms in the system. Do you have a skimmer, run GAC, or employ anything that would limit DOC?

Yes. Yes and not what else I could use to limit DOC.
I also do 40 gallon weekly water changes.


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[reefgeezer]

Yes. Yes and not what else I could use to limit DOC.
I also do 40 gallon weekly water changes.

So, how do you control dissolved organics? Your weekly water changes could export about 15% of the dissolved organics but that could be much less than what is being produced each week.

Carbon dosing or using biopellets can increase organics and actually increase Cyano rather than slowing it down. Either method requires a decent skimmer that is running pretty wet.

 

[RBU1]

I run carbon and have a skimmer. Not sure what your asking.


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[reefgeezer]

I run carbon and have a skimmer. Not sure what your asking.

I was asking for a little more info than "Yes". I wouldn't want to suggest resolutions without knowing. If you have a good, properly sized skimmer, it will help with DOC and enable you to use carbon dosing to reduce nitrate and, to some extent, phosphate. If you decide to carbon dose, I'd suggest using vinegar as it seems to be the least likely to make the Cyano grow faster. BUT...

Your tank is relatively new. With your current water change schedule, simply skimming wetter and sucking out the Cyano aggressively for a while might make it go away without adding anything. Using more GAC and changing it more often can help. Also, be patient and don't overreact. Healthy tanks, particularly young ones. can have a little Cyano or hair algae here & there as long as it's not spreading out of control.