Switching salts help

[reef’r]

RC alk is around 12 I believe, if you are dosing AFR and your alk is 7.5 and your corals aren’t growing I would stop before adding anything else to the tank as there is a serious issue needs fixing, sounds your salinity is extremely low or you are testing it incorrectly because no way on earth should RC be that low.

I would definitely change salt as why use a 12 dkh salt when you want your alk at 9, use a salt with 8.5 or 9 ie either one of the two options you mentioned.

I will add that ~9dkh is where I would like to be so im happy with my RC mixing to 8.9. I believe I tested some fresh mix a few weeks back and it was right around this same number. I use the same alk checker for my tank so I would think readings would be correct

 

[rishma]

I will add that ~9dkh is where I would like to be so im happy with my RC mixing to 8.9. I believe I tested some fresh mix a few weeks back and it was right around this same number. I use the same alk checker for my tank so I would think readings would be correct

I find the alkalinity checker to be reliable as long as the reagent hasn’t gone bad. I’ve had a problem with it going bad multiple times so now I keep it in the fridge. I have been fooled by past reagents going bad and they tend to read a low constant number. DKH of nine for reef crystals is probably right.

 

[reef’r]

Brought a water sample to my lfs and their readings of phos and DKH are way off from mine

 

[Pod_01]

At a quick glance the PO4 is not an issue so I would not focus on that. Alk is different, now the question what value is correct?

Looking at the salinity, that is quite bit of a difference, the lfs claims 1.023 (I am assuming rel. density) and that is about 30 PSU, your value 1.026 (I am assuming rel. density) and that is 34.5 PSU.
I would try to figure out what is the actual salinity, if salinity is off by 10% all of the elements are off by 10%.

I am using this:

It works well for getting repeatable rel. density value… best money I ever spent in this hobby.

 

[rishma]

Phosphate 0.17 vs 0.23 is close enough to be the same in my mind. Neither is a concern.

Alkalinity is a big difference.

Agree you should investigate salinity, I also use that TM hydrometer @Pod_01 posted.

 

[AydenLincoln]

I’ve swapped salts more than once and just do normal and regular water changes and no need to make any other significant changes or adjustments while you do it.