ULNS and alk question

hypnoj

New member
I'm starting to run a ULNS on my SPS tank and I'm wondering the reasoning behind keeping the ALK low for such systems. Any input?
 

Steve Wright2

New member
the theory I have read from a few sources is as follows

the higher Alk encourages faster growth of the coral skeleton
the reduced nutrients of the ULNS systems equal less food for the flesh of the coral

thus the skeleton grows at a rate faster than the flesh can keep up with, leading to expossed tips on the corals

thus many carbon dosers, try and maintain a Dkh of 7.5 to 8 ish

having said that, there are also carbon dosers who maintain higher Dkh without issues, by feeding the corals ( ensuring there is enough nutrients to enable the flesh to grow at a rate identical to the skeleton)

Steve
 

Allmost

New member
the theory I have read from a few sources is as follows

the higher Alk encourages faster growth of the coral skeleton
the reduced nutrients of the ULNS systems equal less food for the flesh of the coral

thus the skeleton grows at a rate faster than the flesh can keep up with, leading to expossed tips on the corals

thus many carbon dosers, try and maintain a Dkh of 7.5 to 8 ish

having said that, there are also carbon dosers who maintain higher Dkh without issues, by feeding the corals ( ensuring there is enough nutrients to enable the flesh to grow at a rate identical to the skeleton)

Steve

that sounds very interesting ! thaks, the best explanation I have seen so far :)
 

Allmost

New member
RTN from the base is related to organic removal too fast.

from the tip is called a tip burn and related to higher alk.
 

hypnoj

New member
RTN from the base is related to organic removal too fast.

from the tip is called a tip burn and related to higher alk.

So it would not be unexpected to get RTN at the base of a small colony if I just replaced all of my GFO and carbon?
 

Allmost

New member
So it would not be unexpected to get RTN at the base of a small colony if I just replaced all of my GFO and carbon?

yap exactly.

when I increase my flow through the Zeo reactor for example too much, the day after all SPS start to die from bottom up ! that removes too much po4 at once chocking the coral.

but no worries, as it would correct itself in a week or so, I have good results dosing AA at those times to help them recover,
 

REEF SMAC

New member
the theory I have read from a few sources is as follows

the higher Alk encourages faster growth of the coral skeleton
the reduced nutrients of the ULNS systems equal less food for the flesh of the coral

thus the skeleton grows at a rate faster than the flesh can keep up with, leading to expossed tips on the corals

thus many carbon dosers, try and maintain a Dkh of 7.5 to 8 ish

having said that, there are also carbon dosers who maintain higher Dkh without issues, by feeding the corals ( ensuring there is enough nutrients to enable the flesh to grow at a rate identical to the skeleton)

Steve

Very interesting. Never heard an actual theory before.


RTN from the base is related to organic removal too fast.

from the tip is called a tip burn and related to higher alk.

Also another interesting experience.

Although I hear a lot of people claim that either one can be caused by Alk swings as well.

Fun topic -

I agree. Very interesting discussion.


As to the OP, great question. I would love to know the answer to this one as well.

Some people report problems with higher Alk, some report no problems with high Alk.

What nutrient being "undetectable" is causing the problem exactly? Phosphate? Nitrate? Both?

How low is too low for these nutrients before you have to start worrying about your Alk level?

Does carbon dosing and how much play into this somehow?

I always wonder how much of a difference there is between two different people's version of a ULNS tank. Is one a ULNS tank according to some test kits and another one is ULNS according to some fancy meters.
Seems like these "ULNS tanks" are all over the map as to how and when they are tested.
Are they tested an hour after the tank is fed or two days after the tank is fed?

Gonna try to follow this one.
 

rc4kinu

New member
So it would not be unexpected to get RTN at the base of a small colony if I just replaced all of my GFO and carbon?
I wouldn't change both at the same time. I usually change carbon 1x month and GFO every six weeks. When the two schedules overlap, I change carbon first and then wait a week and change GFO= no RTN
 
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