ca and mg goes out of wack every water change

[tdsounds]

I been using Randy's recipe 1 for ca, alk, and magnesium. I using 174ml of epsom salt and 293ml of kent tech m after each gallon of the ca and alk. I seem to keep the ca at 390 and alk at 9.6 easily when I test in the morning. I dose about 60ml each part.
Every two weeks I do a water change of about 12gallons. My ca falls to 350 alk stays at 9.6 and the mag is at 1150. Every two weeks when I do the water change I have to constantly tweek the levels to come back. I use Instant ocean salt. Isn't there a better way to do this? I not sure but maybe in the long run this method may not be cost effective for me. Any inputs?

Tank specs

58g
20h sump
Tank full of sps, some softies and lps

[Randy Holmes-Farley]

I use Dowflake to and MAG flake to boost the IO that I use. I boost it by 70 ppm in calcium and 150 ppm in magnesium. I never measure the values in the IO, I just boost it.

This calculator shows how much that would take:

Reef Chemicals Calculator
http://home.comcast.net/~jdieck1/chem_calc3.html

[tdsounds]

Thanks for the info...do you are anyone else know where I can get mag flakes online? Dowflake easy to get online, but I can't seem to find anywhere that sells magflake. Would epsom salt be a good substitute? Thanks again for the help!:rollface:

[Randy Holmes-Farley]

This article has a discussion of it and where it can be obtained. I wouldn't substitute Epsom salts unless there was no other option.

http://reefkeeping.com/issues/2006-02/rhf/index.php#17