Confused and ignorant

[phil bevilacqua]

I see some people having to dose nutritients and talking about running low nutrient tanks.
How does that happen when they feed and dont do water changes ? Do they have so much coral that it eats it all? My phosphate when from .025 to .044 in 3 days when I stopped my GFO and I only have a few fish... a skimmer, algae scrubber and fuge.... I don’t mind running GFO, but why do others have to add nutrients? Hope this even makes sense

 

[NY_Caveman]

LOL, it is crazy, right? I added a large group of SPS frags to my 45 gallon and within a week my nutrients plummeted and Alkalinity and Calcium started dropping. Coralline algae growth also took off around this time. My tank is pretty new and as it was beginning to mature my nutrients were around 5 ppm for NO3 and 0.1 ppm for Phosphate. I was actually working on lowering them in various ways. Then they went right to zero. I had a couple of fish losses around then and had to start dosing Nitrate and Phosphate for a short while.

It often seems half the forum is trying to lower levels while the other half is dosing to hit minimal levels. Every tank is different though and there is no clear answer for every case. In my case I attribute low levels to these factors:

• Low fish bioload
• High coral bioload
• Large, varied clean up crew
• Live Rock
• Protein Skimmer

Not sure any one of them is the answer, but combined it really surprised me my nutrients went to 0.

EDIT: I do a 10% water change every two weeks.

 

[SashimiTurtle]

Growing SPS corals are excellent at nutrient reduction. I've talked with a LFS owner friend and he said on his frag system in the shop he has a hard time getting nutrients in there. Of course it's a fishless, multi trough frag only system with over 500 gallons of water.

 

[Scrubber_steve]

I see some people having to dose nutritients and talking about running low nutrient tanks.
How does that happen when they feed and dont do water changes ? Do they have so much coral that it eats it all? My phosphate when from .025 to .044 in 3 days when I stopped my GFO and I only have a few fish... a skimmer, algae scrubber and fuge.... I don’t mind running GFO, but why do others have to add nutrients? Hope this even makes sense

That difference in PO4 could just be testing varience/error. Leave it a week & test a couple of times before & after. It may rise, but that doesn't mean it will rise too much.
0.1 is a steady state maximum

 

[theMeat]

My 220 has plenty of fish and bio load in a mixed reef. But have 55 gal fuge so no water change in over 3 years. Easy to find nutrient balance between feeding more or less, and length of photo time on fuge. My biggest challenge is trace elements. Alkaline calcium and magnesium are easy, but too many others, and some hard to impossible for a mere mortal to test for

 

[cracker]

Hey Phil, I'm one of those with naturally low nutrients . believe me this comes with it's set of probs also !

 

[Scrubber_steve]

I see some people having to dose nutritients and talking about running low nutrient tanks.
How does that happen when they feed and dont do water changes ? Do they have so much coral that it eats it all? My phosphate when from .025 to .044 in 3 days when I stopped my GFO and I only have a few fish... a skimmer, algae scrubber and fuge.... I don’t mind running GFO, but why do others have to add nutrients? Hope this even makes sense

I would imagine your algae scrubber will also pickup in production now that the gfo is gone, & take up PO4.
My PO4 is fixed at 0.03 & besides a bit of GAC a scrubber is all the filtration I use.

 

[phil bevilacqua]

My 220 has plenty of fish and bio load in a mixed reef. But have 55 gal fuge so no water change in over 3 years. Easy to find nutrient balance between feeding more or less, and length of photo time on fuge. My biggest challenge is trace elements. Alkaline calcium and magnesium are easy, but too many others, and some hard to impossible for a mere mortal to test for

So you just run your fuge longer if your phosphate goes up?

 

[phil bevilacqua]

I would imagine your algae scrubber will also pickup in production now that the gfo is gone, & take up PO4.
My PO4 is fixed at 0.03 & besides a bit of GAC a scrubber is all the filtration I use.

What is Gac?

 

[Scrubber_steve]

What is Gac?

Granulated activated carbon

 

[._Z_.]

It often seems half the forum is trying to lower levels while the other half is dosing to hit minimal levels. Every tank is different though and there is no clear answer for every case.

This sums it up right here.

 

[phil bevilacqua]

What is Gac?

How big a scrubber?

 

[Scrubber_steve]

How big a scrubber?

My scrubber is basically 4 cube by screen size. Its a bit bigger than what I feed the tank, intentionally, but not by 2 x.
I feed nori & mixed minced seafood - prawn pippi mussel squid fish,, plus coral food - phyto reefroids AF Energy, Vitality & Aminos

 

[Scrubber_steve]

So you just run your fuge longer if your phosphate goes up?

The longer algae is illuminated, the more inorganic nutrients (NH3/4, NO3, PO4) it will assimilate over a given period due to photosynthesis.
A good way to determin how long to illuminate your algae for is by NO3 levels. Decide on the level of NO3 you want to maintain, then experiment with what light duration you need to maintain it at that level.

 

[theMeat]

So you just run your fuge longer if your phosphate goes up?

Yes
Although macros generally consume nitrate to phosphate around 4 to 1

 

[Scrubber_steve]

Yes
Although macros generally consume nitrate to phosphate around 4 to 1

Not quite
The ratio of two nutrients that is required for maximal growth of a seaweed is called the optimum ratio. As stated above, the average N. ratio for seaweeds is 30N:1P with a range from 10:1 to 80:1
http://sailing-sea-farm.com/onewebme...v%C3%A6kst.pdf

 

[theMeat]

Not quite
The ratio of two nutrients that is required for maximal growth of a seaweed is called the optimum ratio. As stated above, the average N. ratio for seaweeds is 30N:1P with a range from 10:1 to 80:1
http://sailing-sea-farm.com/onewebme...v%C3%A6kst.pdf

no coffee yet here. In plain English, are you saying macro consumes nitrate to phosphate at 10-80 to 1 ?
Does that apply to both macro as a fuge grows, and more hair algae as scrubber grows?

 

[beaslbob]

I see some people having to dose nutritients and talking about running low nutrient tanks.
How does that happen when they feed and dont do water changes ? Do they have so much coral that it eats it all? My phosphate when from .025 to .044 in 3 days when I stopped my GFO and I only have a few fish... a skimmer, algae scrubber and fuge.... I don’t mind running GFO, but why do others have to add nutrients? Hope this even makes sense

Low nutrients happen with no water changes when if nutrient consumers (algae, corals) are fully consuming the nutrients being generated.

Actually water changes only reduce changes not prevent build ups and depletion. Hence, the dosing schemes to maintain calcium and the like. What happens is the tank builds up to where the nutrients removed by the water changes equal the buildup between water changes. For instance, if you have 1ppm per day increase in nitrates and change 10% of the water every 10 days the tank builds up to where the nitrates before the water change is 100ppm. After the water change you have 90ppm which rises to 100 before the next change.
By contrast, in a system balanced out with algae you simply have 0ppm nitrates regardless of the water changes. Even no water changes.

my .02

 

[Scrubber_steve]

no coffee yet here. In plain English, are you saying macro consumes nitrate to phosphate at 10-80 to 1 ?
Does that apply to both macro as a fuge grows, and more hair algae as scrubber grows?

As I uderstand it the Redfield ratio > 106:16:1 > carbon:nitrogen/Posphorus is the ratio for micro algae > phytoplankton.
The paper I provided a link to states that the ratio of Nitrogen to Phosphorus take up by macro algae varies considerably depending on species, as well as "various physical, chemical, and biological factors".
The variation is from 10:1 to 80:1 Nitrogen/Phosphorus

 

[Captain Quint]

Great thread with great info.

Most importantly phil bevilacqua. You are not ignorant.