Macro Nutrient Uptake

[jduong916]

When macro gets big and stops growing is it still taking up nutrients? Or does it only take up nutrients when it growing?

 

[nautical_nathaniel]

When macro gets big and stops growing is it still taking up nutrient? Or does it only take up nutrients when it grown?

Algae still needs nutrients to maintain photosynthesis and cell growth/replacement, so it is still doing it's job and consuming nutrients. I's probably still growing too, it's just gotten to the size where it is hard to notice changes and growth rate has slowed in response to fewer available nutrients.

 

[jduong916]

Algae still needs nutrients to maintain photosynthesis and cell growth/replacement, so it is still doing it's job and consuming nutrients. I's probably still growing too, it's just gotten to the size where it is hard to notice changes and growth rate has slowed in response to fewer available nutrients.

So why do we need to trim the macro? If it's big and consuming nutrients what is the reason for trimming it.

 

[Randy Holmes-Farley]

I don't think macroalgae can be doing much useful for nutrients if it is not growing.

The N and P taken up go into biomolecules of new tissue.

 

[nautical_nathaniel]

So why do we need to trim the macro? If it's big and consuming nutrients what is the reason for trimming it.

Trimming is a form of export, i.e. removing the nutrients stored in the tissues of the macro algae from the system for good.

 

[Yuyiboy]

The actual nutrient removal takes place when you physically throw it out. If there are less nutrients to keep it growing fast, then decreasing the size helps it stabilized. Plus I wouldn’t want it dying off and releasing all that into the tank. Just a thought.

 

[Dom]

When macro takes up nutrients, it is more of a containment of the nutrients. The "export" doesn't happen until you physically remove some of the macro.

 

[jduong916]

I don't think macroalgae can be doing much useful for nutrients if it is not growing.

The N and P taken up go into biomolecules of new tissue.

So, correct me if I'm wrong, in order to sustain life (not growing) Macro does not need N and P, just light and whatever else a plant needs for survival. When macro grows it take up N and P as biomass. So the N and P is only consumed to create the structure.

 

[Randy Holmes-Farley]

So, correct me if I'm wrong, in order to sustain life (not growing) Macro does not need N and P, just light and whatever else a plant needs for survival. When macro grows it take up N and P as biomass. So the N and P is only consumed to create the structure.

That's basically what I said, although it has limitations.

When it comes right down to sustaining life without growth, I suspect some N and P is needed, but some is also being lost (dead cells, organic molecules lost, etc.). I'm actually not sure macroalgae can survive for a long periods without growing, however.

 

[Newb73]

That's basically what I said, although it has limitations.

When it comes right down to sustaining life without growth, I suspect some N and P is needed, but some is also being lost (dead cells, organic molecules lost, etc.). I'm actually not sure macroalgae can survive for a long periods without growing, however.

Last year I had a large colony and just removed 90% of it.

The colony had not been growing much under a Kessil A150 anyway. It had taken well over a year to achieve its size that many can grow in weeks.

Even though it had not been growing....removing most of it correlated with a large spike in N and P and an increase in nuisance algae.

This lead me to believe even a non growing patch is consuming a fair amount of nutrients just to sustain itself.....in the same way I am blessed with being able to consume a boat load of pizza and not gain a pound.

That became academic when I upgraded to Kessil grow lights of course because it grows very fast now.

 

[DeepBlueSomething]

Following this discussion with interest.

My chaeto has gone from tennis ball to softball size in the past 2 weeks - and I feel like the nuisance algae growth has leveled a bit. It does make me wonder is it better to keep a smaller but rapidly growing macro or a large and slower growing...

 

[jduong916]

Last year I had a large colony and just removed 90% of it.

The colony had not been growing much under a Kessil A150 anyway. It had taken well over a year to achieve its size that many can grow in weeks.

Even though it had not been growing....removing most of it correlated with a large spike in N and P and an increase in nuisance algae.

This lead me to believe even a non growing patch is consuming a fair amount of nutrients just to sustain itself.....in the same way I am blessed with being able to consume a boat load of pizza and not gain a pound.

That became academic when I upgraded to Kessil grow lights of course because it grows very fast now.

That Kessil rocks. I have the H380 and the macro grows and grows. I kind of think that if the algae is huge and its not growing, or noticeably growing then your N and P levels should already be low. Why trim it? If the N and P rises shouldn't the macro grow start to grown again?

 

[Randy Holmes-Farley]

Even though it had not been growing....removing most of it correlated with a large spike in N and P and an increase in nuisance algae.

This lead me to believe even a non growing patch is consuming a fair amount of nutrients just to sustain itself.....in the same way I am blessed with being able to consume a boat load of pizza and not gain a pound.

lol

Ignoring the pizza analogy, where would the N and P taken up by the macroalgae be going?

The only possibility is released organic molecules, and if you do not export them, they get recycled, releasing the N and P.

 

[madweazl]

When I first started the refugium, I was just letting it grow out because I had lots of open space. After about six months, I started removing a substantial amount to "export" the nutrients. After a few months of doing this, nitrate and phosphate levels started to creep up so I decided to leave it alone again. For the past two or three months I haven't messed with it and levels have come down again. Anecdotally, this seems to suggest it is best for me to leave it alone and just let it do whatever it is doing down there. I haven't removed any and it is so dense it's hard to know what is going on down there.

 

[Newb73]

lol

Ignoring the pizza analogy, where would the N and P taken up by the macroalgae be going?

The only possibility is released organic molecules, and if you do not export them, they get recycled, releasing the N and P.

Lol....us complex organismns are blessed by a high catabolic requirement just to maintain a resting state (thermoregulstion, glycolysis, oxygenation, protein synthesis etc)


Still, even in a simple life form one might reasonably assume there are at least SOME Internal metabolic processes such as oxygenation and nutrient transport around the cells, some level of iron uptake and photosynthesis to maintain color etc. are bound to be using some energy.

I am no plant biologists but I believe that's correct.

 

[Newb73]

When I first started the refugium, I was just letting it grow out because I had lots of open space. After about six months, I started removing a substantial amount to "export" the nutrients. After a few months of doing this, nitrate and phosphate levels started to creep up so I decided to leave it alone again. For the past two or three months I haven't messed with it and levels have come down again. Anecdotally, this seems to suggest it is best for me to leave it alone and just let it do whatever it is doing down there. I haven't removed any and it is so dense it's hard to know what is going on down there.

You are likely loosing efficiency by not removing ANY......anything that dies on the bottom gets it's nutrients consumed by living areas but a homeostasis gets achieved where you are not removing much net nutrients from the tank.

Try removing smaller amounts more frequently.

 

[madweazl]

You are likely loosing efficiency by not removing ANY......anything that dies on the bottom gets it's nutrients consumed by living areas but a homeostasis gets achieved where you are not removing much net nutrients from the tank.

Try removing smaller amounts more frequently.

At this point, I don't need it to remove any more than what is currently happening so there isn't any reason to do so. If/when things start to rise again, I can try that.

 

[Randy Holmes-Farley]

Lol....us complex organismns are blessed by a high catabolic requirement just to maintain a resting state (thermoregulstion, glycolysis, oxygenation, protein synthesis etc)


Still, even in a simple life form one might reasonably assume there are at least SOME Internal metabolic processes such as oxygenation and nutrient transport around the cells, some level of iron uptake and photosynthesis to maintain color etc. are bound to be using some energy.

I am no plant biologists but I believe that's correct.

Sure, there's lots of need for lots of things to maintain life. But you are missing the simple point that N and P cannot be created or destroyed. If it is not going into new tissue, then it is either not being taken up, or is being released again.

 

[Newb73]

Sure, there's lots of need for lots of things to maintain life. But you are missing the simple point that N and P cannot be created or destroyed. If it is not going into new tissue, then it is either not being taken up, or is being released again.

Fair enough.

I suppose a seemingly stable colony may actually be growing thicker but isn't really observable from just viewing it in the sump, giving the impression that it's not growing when it is.

Following that line of thought....removing too much will spike your levels......but never removing ANY also means it's a ticking time bomb until it reaches critical mass and crashes (I would assume).

 

[jduong916]

Sure, there's lots of need for lots of things to maintain life. But you are missing the simple point that N and P cannot be created or destroyed. If it is not going into new tissue, then it is either not being taken up, or is being released again.

That still doesnt explain the need to trim macro. If it's large and not growing then you should be fine because their isn't enough N and P. If the macro starts to die then the N and P would rise and the macro should start growing again.

I suspect the macro is still growing just very slowly and not noticeably, but the macro is doing its job removing whatever little N and P is left.