Can i dose only Alk?

[sticksreef]

Hi, i have a 55g net water volume system up for a few months, have around 9 small frags (sps, lps zoas) and 10 turbo snails with 3 fish.

The question is: can i only dose ALK? Since all my other parameters are not getting consume: calcium is at 450, mag 1400. Have been like this for months.

Only thing dropping is the ALK. Should i dose baking soda? If so how and how much? I calculated the ALk consumption around 0.5 dkh per day. I have the ati essentials just dont think its necessary for now since calcium and mag are high.

Current parameters:
Calcium 450
Mag 1400
Ph 8-8.2
Nitrates 5ppm (dosing)
Phos near 0

Thank you!

 

[shaggydoo]

Yes, you can dose alk by itself. My tank's alk drops quickly (as does my Mg) but my Ca has never gone below 450 and I rarely dose Ca, but I'm always dosing various alk and mg supplements. I've never used baking soda, but should work. I just get alk supplements from my LFS.

 

[Randy Holmes-Farley Verified Community Expert]

You can, but your initial assertion of only alk getting consumed is not likely true. You just cannot readily detect the slow changes in calcium based on your alk depletion rate. It is only about 3 ppm per day, and water changes may also be disguising that.

The problem with just assuming (incorrectly) that calcium is not depleting is that once you see the drop (say, once it has dropped 40 ppm), you'll likely need to add back about the same as you would have been dosing all along if you just used a balanced calcium and alkalinity addition method.

Also, if you are at 450 ppm calcium now, you are apparently using a salt mix with high calcium in it. A balanced additive will keep it where the salt mix starts (same for magnesium), but if you actually want them lower (say, 420 ppm calcium), you may need to allow them to drop without dosing.