Milliepora tip turned brown

[Pennywise the Clown]

The tip of one of my millies has turned brown. I have recently changed lighting spectrum to the BRS AB+ on my Hydra 26's but the par is not as high as my previous schedule.
I have also removed a large birdsnest which has resulted in my alkalinity and calcium levels slowly rising. I have reduced dosing levels to bring these levels down a touch.
Alkalinity 9.6 (usually 9)
Calcium 450 (usually 440)
Mag 1350
Phosphate 0.1
Nitrate 5
All my other sps are doing and growing well.
Is this a problem and if so, an

ything that I can do?

 

[Reefer40b]

Higher alk usually causes burn tips not much to do here but lower the alk like you did and stabilize.

 

[Crystal clear]

Tip is dead

 

[Justfebreezeit]

Clip the tips if it starts to spread. Should heal and resume normal operation.

 

[MrNYCeGuy]

Higher alk usually causes burn tips not much to do here but lower the alk like you did and stabilize.

Agreed with Reefer40b, looks like burnt tips, your Alk is too high for your level of nutrients. If NO3 is around 5 then your Alk should be closer to around 7.5- 8. The more nutrients in your tank the higher you can keep your Alk...the inverse of that statement is true as well.

Here is your proof: https://www.advancedaquarist.com/2015/5/aafeature

 

[Pennywise the Clown]

Very interesting. I had no idea there was such a relationship between nutrients and alkalinity.
I will definitely lower my alk, but do it slowly.

 

[MrNYCeGuy]

Yes, go slowly when you decrease the Alk. I like to let mine fall naturally and raising it slowly. You may also choose to increase your nutrients as well...Here is a thread that talks about just that : https://www.reef2reef.com/threads/w...nutrients-for-high-end-sps-coloration.656329/

 

[jda]

Very interesting. I had no idea there was such a relationship between nutrients and alkalinity.
I will definitely lower my alk, but do it slowly.

Higher levels of N and P will inhibit calcification... different degrees for different acropora, but all of them slow down as N and P rise, but still grow. Calcification is faster with lower levels of N and P. Natural Seawater keeps alk around 6.8 to 7.0 to slow/limit the calcification process down in the presence of low N and P. In an aquarium, higher alk will give the calcification process too much fuel and it will run wild and create skeleton faster than the tissue can keep up... and you get exposed tips that die.

There is no harm in keeping alk near 7, which is what it is in the ocean.