KH level in Sps tank

[Billyreef-ita]

Hi everybody,
I have a question regarding the optimal KH level in Sps dominant tanks.
My 75g contains many SPS but pretty “easy” ones (montipora). My current KH level tested with Hanna checker is 5dkh.
The corals are fine in my opinion, I attach a photo of one of the montiporas for your evaluation.
I’ve noticed each time I try to increase the KH at least at 7, they start suffering (polyps retraction, no growth).
I tested also with AQuaforest, just in case my Hanna reagent was somehow failed, but I got even lower KH (4.8).

My question is: do I continue trying to increase KH up to 6-7 and maybe this time resisting for a longer period waiting the corals get used to the new level, or leave KH as it is now?

Thanks

 

[littlebeard]

5 is lower than most people run. How fast are you trying to raise the alk? Corals don't like swings.

What is the alk of your water change water?

 

[Randy Holmes-Farley Verified Community Expert]

I recommend keeping alk at 7-11 dKH. I definitely would not allow it to remain at 4.8 dKH. :)

 

[Billyreef-ita]

5 is lower than most people run. How fast are you trying to raise the alk? Corals don't like swings.

What is the alk of your water change water?

Maybe I’m doing it too fast, what could be a period of time suitable for reaching gradually 7, one month?

 

[Randy Holmes-Farley Verified Community Expert]

Maybe I’m doing it too fast, what could be a period of time suitable for reaching gradually 7, one month?

I'd raise alk from 5 to 7 dKH in 4 days.

 

[Billyreef-ita]

I recommend keeping alk at 7-11 dKH. I definitely would not allow it to remain at 4.8 dKH. :)

Yes I read your recommendation in other threads that’s why I was targeting 7

 

[Billyreef-ita]

I'd raise alk from 5 to 7 dKH in 4 days.

Last time I did it in one week, but the impact was bad, I’m trying again

 

[Randy Holmes-Farley Verified Community Expert]

Last time I did it in one week, but the impact was bad, I’m trying again

Have you validated your test result somehow?

 

[Billyreef-ita]

I keep on double checking Hanna checker and Aquaforest kit each time I try to increase all.
no ICP test so far

 

[Dburr1014]

How about the other tests?
Cal
Mag
Nutrients

I've been down to 6 in the past but below that is difficult to get there.

 

[Billyreef-ita]

Cal - 450 ppm
Mg - 1500 ppm
PO4 - 0.02
NO3 - 0.0