Quick Dropping Alk


New member
I have a strange dilemna in my tank right now. I checked today to see what my alk was and it came back really low (1.6 meq/L). So I mixed up some Baking Soda and Baked Baking soda in a container with fresh water until it was clear and poured it in. I got the measurements from the calculator. Alk came right up and maxed out my crappy Red Sea test kit (3.9 meq/L). I know I need a different kit, I just ordered one. So I know my dKH is at least 10.92 since 3.9 meq/L = 10.92dKH. :eek1:

Then, I check it about 4 hours later and its back down to the same 1.6 area. Bummer. I even checked it twice. :mad2:

Any Ideas what would be causing this? My calcium is a little high right now (520) I'm letting it come down on its own.

Here's my setup and params.
45Lbs LR
60LBS of LS (I just added 20lbs more a few days ago)
I'm also running carbon.

Temp 80.3*
Specific Gravity 1.025
Ph 8.4
NO2 0
NH3 0
NO3 0
PO4 0
Ca 520

I dose Calcium Chloride (mixed in FW, then poured in), but I havent added any in a while. I use half regular baking soda and half baked baking soda to not make a big pH change. I also have C-Balance but I haven't used any yet. I have Kalk (pickling lime) that I started dosing overnight slowly tonight.
5% water changes every week (Reef Crystals Salt & RO/DI)
The tank has been up for just over a month, has no fish, a few coral frags, 8 turbo snails, a few hermits, crabs, etc.

I have also noticed in the top corners around the tank is a whiteish colored hard film. I assume it might be some kind of precipitate.

So why is my Alk dropping so fast?:eek2:


Premium Member
Are you seeing any signs of precipitation? Like a whitish snow effect? If not, I suspect the test kit is not working properly. I'd stop the large doses, at least, until you get a new test kit.

I am somewhat biased, since I had bad experiences with my Red Sea test kits, and had to return them.


New member
Unless your test kit is bad, the most likely explanation would be your whitish film is CaCO3 precipitation. I would suggest just using baking soda in the future. It won't drop your ph other than a possible temporary very small drop. With really high calcium, a high ph is going to encourage the precipitation.


Premium Member
Wow, I'm having problems with reading lately. Sigh. I think you'd see more precipitation than that, though, to cause that much change in alkalinity.