Low alk, higher Ca and Mg

puffy127 · Jul 12, 2016

I would like to start dosing kalk in my ATO, by my alk levels are low (~6.1 dKH) with higher Ca (450 ppm) and Mg (1485 ppm) levels. I have not ever dosed any supplements or kalk in my tank. This is with Reef Crystals only, which raises levels to around 7.7 dkH, 500 ppm Ca and around 1500 ppm Mg after a wc. Should I try raising only alk before adding kalk to my ATO? How do I deal with the elevated levels after a wc?

twilliard · Jul 12, 2016

Just dose alkalinity till you hit your target level.
Do it slow as to not start precipitation

Randy Holmes-Farley · Jul 13, 2016

You can either bump the alk up with baking soda, or you can more slowly raise it with the kalk.

Low alk is not a reason to delay using limewater (kalkwasser).

CodyRVA · Jul 13, 2016

Randy Holmes-Farley said:
You can either bump the alk up with baking soda, or you can more slowly raise it with the kalk.

Low alk is not a reason to delay using limewater (kalkwasser).

Does baking soda have the same affect on PH as Soda Ash or another equivelant?

Randy Holmes-Farley · Jul 13, 2016

Baking soda will not boost pH (actually has a very slightly pH lowering effect). If you want a pH boost, you can bake it first at 400 deg F for about an hour. That heating converts the sodium bicarbonate (baking soda) into sodium carbonate (soda ash or washing soda).

puffy127 · Jul 13, 2016

Thanks Randy.

Randy Holmes-Farley · Jul 13, 2016

You're welcome.

Happy Reefing!

puffy127 · Jul 13, 2016

Ok, so I baked some baking soda. According to the reef calculators, I need 2.2 tsp to raise the alk by 1.4 dKH. How do I do this? Dissolve it in how much RODI? How slowly do I need to add it?

puffy127 · Jul 15, 2016

I found out the reason my Ca and Mg levels were so high was because my refractometer was off and I was putting too much salt in my sw for wcs. I've corrected the issue and everything is on target now. I've also added baking soda to increase the alk in my DT and put kalk into my ATO reservoir.

However, my alk is still low in newly mixed sw. Should I add baking soda into the new sw to match the alk in the DT prior to doing water changes?

Randy Holmes-Farley · Jul 15, 2016

Most salt mixes have plenty of alk and I would not generally boost them before using. What mix are you using?

Yes, dissolve the sodium carbonate in RO/DI and how much is up to you as long as it dissolves. Getting more than 2 cups per gallon of RO/DI will be challenging to dissolve. 1.4 dKH can be added at once, or spread out.

puffy127 · Jul 15, 2016

Reef crystals. Newly mixed is around 7.6 dKH and my DT will be around 9 (after I finish with the baking soda).

Randy Holmes-Farley · Jul 15, 2016

puffy127 said:
Reef crystals. Newly mixed is around 7.6 dKH and my DT will be around 9 (after I finish with the baking soda).

There is some problem because reef Crystals mixes much higher and does not need supplemental alk.

Isaac Alves · Jul 16, 2016

Randy Holmes-Farley said:
There is some problem because reef Crystals mixes much higher and does not need supplemental alk.

What are the values for a properly mixed batch of Reef Crystals for Alk, Mag., Calcium?

Randy Holmes-Farley · Jul 17, 2016

Varies with salinity, but something on the order of 12 dKH for alk, calcium in the low 400 to mid's and magnesium in the low to mid 1300's.

Mandrew · Jul 17, 2016

My RC mixes at 12dkh and around 420 calcium. Not sure on mag.

jaws789832 · Jul 17, 2016

My Rc mixes around 7.6 as well using the hanna checker which I thought was odd. I pretty much check every new box, 7.6 dkh, 1450 cal, and 1500 mag give or take

puffy127 · Jul 17, 2016

My RC has consistently been measuring at alk below 8, Ca around 450 (both Hanna) and Mg around 1350 (salifert). I double checked my alk and Ca with salifert and get roughly the same numbers.