Alk steadily decreasing, while CA is not moving

[Randy Holmes-Farley Verified Community Expert]

So it's not okay to only dose for alk daily?
I dose b-ionic part 1 to keep my alk between 8.5-9, calcium barely drops 5-10ppm a day. I raise my calcium only when i do a water change.

"OK" is relative term. If you use a salt mix with a lot of excess calcium, the salt mix may supply enough calcium for quite a while when only dosing the alk part of a two part.

If you dosed both parts equally to maintain the alkalinity, the calcium and alk will stay at about the same level as in the salt mix.

 

[Randy Holmes-Farley Verified Community Expert]

Hello Randy, Im not sure how much more ML to add to my dose. Can you help me out with it? ATM I'm Dosing 30ml total for 1+2 part, should I go incriments of 5ML or lower?

Use this calculator to determine a revised dose:

http://reef.diesyst.com/chemcalc/chem_calc3.html

 

[Randy Holmes-Farley Verified Community Expert]

I'm not saying I have a huge parameters problem but it seems the only thing to be dropping is my alk and magnesium. 40gal system total. I dose 2ml of cal a night, 30ml of alk a night to get it to raise but is staying stabil at 8.4-9.6, and I check magnesium every 4 days and seems to be dropping about 200ppm every 4 days. I don't have dosing pumps I do it by hand. I think kinda what my issue is, is that my system is only 70-80 days old so should I be patient and let my system age and at the same time keep up with my dosing and keep an eye on my parameters?

There's no mechanism in any normal reef tank for magnesium to decline more than calcium declines.

If there's one think I can absolutely guarantee in reefing is that your magnesium cannot possibly decline 200 ppm in 4 days. Maybe in a year it could drop that much in a heavy SPS tank with no magnesium additions or water changes.

In a tank like yours, magnesium will reflect the salt mix and not have changed noticeably.

Assuming you are using a quality name brand sat, I'd just stop measuring magnesium.