Alk that drops Fast?

[Snowboarda42]

I have noticed every time I check my tank's water param's, my alk always has dropped MUCH faster than my Ca.

Take today's test for instance, using my Salifert tests:

Ca - 440
Alk - 6.4dKh

I dose Randy's 2 Part.

I then bumped my Alk back up to 10.

I aim for an Alk of 10, and the balanced ratio is 432Ca, yet my calcium always drops at a MUCH slower rate. I don't have a Mg test right now (no local LFS has them), but I do 15% water change each monday with Reef Crystals religiously.

40B, 45Lbs LR, 80lbs LS
ph - 8.6 (I think I need to calibrate this...)
Temp - 81.0*

Tank Livestock is as follows: (click pic in my sig)
11 SPS frags (all growing nicely)
1 LPS
1 Deresa Clam
~50 Heads of different zoos,
1 rock covered in Anthelia
Xenia
2 Ricordeas
1 Hairy Mushroom
GSP
(If you need more specifics on type, just ask)

I also have the usual snails, crabs, fish, and conch...

Any reason why my Alk drops so much faster than my Ca? I thought they were supposed to go around the same rate?

 

[DonW]

That is normal. Just up your daily dose of alk suppliment.

Don

 

[Boomer]

That is because your Alk demand is higher than you Ca++ demand, which is as Don stated quite normal. For every 20 ppm Ca++ that you loose you will lower the Alk 2.8 dKH. The rest goes to other chemical reactions, such as some of those in neutralizing acids produced in the tank from other chemical reactions and food/animal/plant wastes.

 

[Snowboarda42]

Oh gotcha. Thanks!

/Thread