Water chemistry issues

I am new to the salt hobby and I have a 150g reef aquarium, my current chemistry is:

Calcium 420
Magnesium 1170
Salinity 1.024
pH 7.98
Alkalinity 15.4

I was told by a lfs I had to raise my ph, so they told me to add seachem buffer. Which I did with water top offs and tank changes, and my ph stayed between 8.1 -8.3. But a friend said I should check my other levels and everything had dropped, cal 400, mag 1155 and my alk was through the roof 16 +. So I've stopped adding buffer and just add some calcium and mag, but my alk isn't coming down. Is this a problem? How do you get alk down? Should I be worried? Thanks for your help/advice.

I use Tropicmarin proreef and my change water is as follows:
calcium 405
magnesium 1275
alk 11.2

 

bump

 

Buffers tend to affect your alk as you've found out. I wouldn't bother chasing PH if it's not horrific (horrific being like under 7.7), as long as the room is well-ventilated and your alkalinity is fine your PH should be fine too. You could do a 20% water change if it really bothers you, or just wait until your coral have consumed the alk down to a level that you like and then you can resume dosing.

Here's more info on PH:
http://reefkeeping.com/issues/2007-05/rhf/index.php

And more info on chemistry basics in general:
http://reefkeeping.com/issues/2007-04/rhf/index.php

 

the level of dissolved CO2 in the water effects the alkalinity and pH.
If you can increase dissolved O2 in the water your pH will stabilize and your alk will decrease

 

go ahead and boost your mag up to 1500 ppm, but no more than 100 ppm per day!!! then get your calcium up to at least 450 ppm. this alone might drop your alk, but if it don't i wouldn't worry about it. just ride it out until next water change. you will have to test your fresh saltwater for the mag and cal levels that i said earlier(most likely you will have to add mag and cal ). don't worry about the 100 ppm per day since your tank will already have the correct levels, go ahead and get it where it needs to be.
mag at 1500ppm, cal at 450ppm and alk at 12 dkh
sodium carbonate will raise your ph, sodium bicarbonate will lower your ph
both will raise your alk. keep up with these parameters and it will eventually even out with the correct ph. i used to have constant low ph values of 7.8, now it is at 8.3 to 8.4 sometimes it gets a little high so i will use sodium bicarbonate (baking soda) to raise my alk.