Help me understand the relationship between high and low parameters

[MONTANTK]

In 2021 I’d like to learn a lot more about reef chemistry. I’ve already seen a lot about people running tanks very successfully with higher Po4 and No3 than what would have been considered acceptable say 5 years ago. So what is the relationship between having low Alk and/or Mg and Ca when Po4 and No3 is 0 or close to it and vice versa?

Part of my curiosity is stems from my tank having 0 detectable Po4 and No3 and Alk around 8 with Mg and Ca at 1500 and 500, respectively. I am working on lowering Mg and Ca.

 

[blasterman]

Basically we are running Po4 and No4 higher as long we aren't getting a lot of nuisance algae or any other blooms. This can be tricky with younger tanks where competitive biologies haven't had time to set up shop yet, so you are kind of playing with fire and need to keep a close eye on things.

Ca and Alk levels have nothing to do with Po4 and No3, although with higher nutrient levels you will certainly see higher alk consumption.

If you are nutrient locked you can fiddle with alk and ca all you want - it won't make corals grow faster. Having stable nutrient levels and little to no amounts of nuisance algae will improve coral growth faster than any other parameter in my opinion. Ca at 400-450'ish and alk at 8-9'ish.

 

[MONTANTK]

Basically we are running Po4 and No4 higher as long we aren't getting a lot of nuisance algae or any other blooms. This can be tricky with younger tanks where competitive biologies haven't had time to set up shop yet, so you are kind of playing with fire and need to keep a close eye on things.

Ca and Alk levels have nothing to do with Po4 and No3, although with higher nutrient levels you will certainly see higher alk consumption.

If you are nutrient locked you can fiddle with alk and ca all you want - it won't make corals grow faster. Having stable nutrient levels and little to no amounts of nuisance algae will improve coral growth faster than any other parameter in my opinion. Ca at 400-450'ish and alk at 8-9'ish.

Ah okay I see. Right now I barely have any algae and I’m seeing solid growth out of my corals. I am definitely a little cautious about the low nutrients since my tank is still young but I’m testing daily or every other day depending on the parameter

 

[ASIN28]

Basically we are running Po4 and No4 higher as long we aren't getting a lot of nuisance algae or any other blooms. This can be tricky with younger tanks where competitive biologies haven't had time to set up shop yet, so you are kind of playing with fire and need to keep a close eye on things.

Ca and Alk levels have nothing to do with Po4 and No3, although with higher nutrient levels you will certainly see higher alk consumption.

If you are nutrient locked you can fiddle with alk and ca all you want - it won't make corals grow faster. Having stable nutrient levels and little to no amounts of nuisance algae will improve coral growth faster than any other parameter in my opinion. Ca at 400-450'ish and alk at 8-9'ish.

When you say nutrient locked, what do you mean by that? P04 and NO3 at 0?

 

[Randy Holmes-Farley Verified Community Expert]

The high magnesium and calcium (whether accurate or not) have no relationship to the low nutrient levels (whether they are accurate or not).

 

[MONTANTK]

The high magnesium and calcium (whether accurate or not) have no relationship to the low nutrient levels (whether they are accurate or not).

Thank you! I saw some people on the forum who have suggested that Alk should be higher if nutrients are lower and I was just curious why that was the case

 

[Randy Holmes-Farley Verified Community Expert]

Thank you! I saw some people on the forum who have suggested that Alk should be higher if nutrients are lower and I was just curious why that was the case

The observation with high alk and low nutrients is burnt tips on some SPS corals.

High alk makes certain SPS corals grow skeletons faster, and the working hypothesis of what happens is that tissue growth in low nutrients cannot keep up with skeletal growth, leading to thin tissue at the tips that is easily damaged.

 

[MONTANTK]

The observation with high alk and low nutrients is burnt tips on some SPS corals.

High alk makes certain SPS corals grow skeletons faster, and the working hypothesis of what happens is that tissue growth in low nutrients cannot keep up with skeletal growth, leading to thin tissue at the tips that is easily damaged.

That makes sense. Thank you!