I would try and get your mag up in the 1300's. What brand salt do you use? Also judging by going to the fish store to get the test done Im guessing you dont test yourself regularly?
I typically have the fish store test the water for me on a near weekly basis. I had a person there that I actually trusted and became friends with. He however, left for college in Arizona. Now I can't trust them as far as I can throw them.
With that being said, I purchased a CA/ALK kit from the local reefers and it is in the mail, and yesterday I picked up a MG kit so I can conduct the tests myself.
I tested 1130ppm MG yesterday night vs. 1020ppm that the store had, so one of us is off... However, I ended up dosing 70ppm worth of MG last night and after about 2.5 hours of addition, I noticed it increasing by about 10ppm. This morning I retested MG and it is now at about 1160ppm. Which I have now dosed another 70ppm and I will retest once I get home from watching Michigan Football Practice! :bounce2: I am currently using the BRS 2-part solution to make any adjustments to the MG -- it appears that the MG mix is a combination of Magnesium Chloride and Magnesium Sulfate.
According to the numbers that the LFS gave me, it seems that all of my parameters are just slightly low from what I have read. However, with the discrepency in the Mg, I don't know if I can trust the Ca/Alk numbers until I can gain better fidelity on what is truly going on.
As far as salt and water changes are concerned... I have a 30g tank with a sump. I would estimate I have a total water volume of 35g. I change 5 gallons every week pretty consistantly. Each week I swap between Instant Ocean and Aquavitro Salinity. Once those buckets run out I'm just going to run Reef Crystals from here on out.