Nutrient Questions

[Maho.B]

Hello everyone, I have a scenario I would like to run by you for your opinions. I just got back last night from a week in Aruba and did a full test this morning to see how things were doing. First of all, I should lead with my initial observations of when the lights came on this morning. Not only is every coral looking great, they seemed to have had a "growth spurt" during the week we were away. Now I realize when you see the tank multiple times daily, then you don't see it for a week it will seem like there was growth, but this is strange. All of the sps have considerably more growth than usual. For example, several of the Acropora that have had a lot of the encrusting area on the rock have been that way for months, with all of the growth on the branch tips, now the encrusted areas have multiple branches starting to pop up out all of a sudden.

Okay, the odd part now. The Alk is MUCH lower than it has ever been.

Here are the nutrients I have kept the system at for the last year:

Alk: 7.7 - 7.9
Phos: .03 - .05
Nitrate: 7 - 9
Calcium: 430 - 450
Magnesium: 1350
Salinity: 35
Temp: 77

I keep these stable by dosing soda ash with a dosing pump throughout the day and manually dosing the others as needed after testing. I use Hanna for Alk, Nitrate and Phosphate, and Salifert for calcium and magnesium.

Here are the nutrients measured this morning after being gone for the week. Keep in mind, the alk had still been dosing as normal while gone and I did the manual dosing of the others prior to leaving.

Alk: 6.7
Phos: .05
Nitrate: 3.3
Calcium: 375
Magnesium: 1300
Salinity: 35
Temp: 77

So my question to you is mostly about the Alkalinty. It has NEVER been below 7.2 so the reading of 6.7 really threw me off...as did the crazy amount of new growth which is odd since I always heard you run high alk for faster growth. So, do I slowly increase the dosing pump over the next week to get it back to the range I normally keep it? 6.7 just seems to low. Or would you keep it as is since everything looks great? Also a little odd is the calcium. Week after week it consistently drops around 10 to 15 ppm and this week while gone it dropped 50 ppm.

Any thoughts on the Alkalinty (raise it back up or keep it where it is) would be great. Sorry for the long post for an Alk question, just wanted to give you some background. Thanks!

 

[CHSUB]

I run Alk ~7 sometimes it goes lower, in the past ran Alk at ~9. Don’t really notice a difference between either. In your case, I would increase the dosage amount slightly to maintain this new lower reading, but imo it makes little difference at either level.

It doesn’t surprise me, however, lower nutrients resulted in improvement in growth. This is why we run nutrients low but available.

 

[Maho.B]

Thanks. I bumped up my dosing pump 14 ml (on a 110 gallon system) and will run it like that for a few days testing daily to see how it goes. Thanks