common for tank to SUCK DOWN alk?

[t4zalews]

So I'v been having problems keeping my alk up. my Ca says around 420-450 using API test kit. My Mag 1350-1400 tested with salifert. and my alk is hovering around 5-6 with API test. I've started to boost it up with baking soda as my my Ph stays above 8.

I've been really trying to lower my phosphate as low as possible, went from about .07 to .03 using hanna photometer.I've noticed much more coraline algae growth lately. Should I start mixing baking soda with my top off water to keep alk up? if so how much do you think for a 5 gallon resevoir. I usually go through about 5 gallons of top off every 4-5 days. but its winter too in michigan.

65g sps with clams.

is it normal for just alk to be used up so quickly? I thought that the 3 had a balanced relationship when it comes to calcium consumption.

[bertoni]

Most tanks require daily alkalinity and calcium supplementation. A drop of 2 dKH per day is fairly common. Using the topoff water to dose alkalinity is fine, or you could consider a two-part, which is a bit easier to handle. The calcium seems to drop more slowly because there's so much more of it in the water. For every 2.8 dKH drop, only 20 ppm of calcium is consumed, which is close to the resolution of many kits.

I'd guess the coralline and the clam are the major consumers of calcium and carbonate in your system. :)