Ca/Alk Triumph!

[rmurken]

I think I just had my first success enhancing calcification by judicious use of an Alk supplement!

So my tank (55g reef) is about a year old and coralline algae is starting to come in. I also have a few non-coral inverts that incorporate CaCO3, but my Ca (430ish ppm) and Alk (low 7’s dKh) wouldn’t drop much between weekly 10% WCs. So not much calcification, which is a downer and supports my empirical observation that coralline growth is sluggish.

I am stubbornly committed to using plain old IO—part of the fun for me is testing and supplementing. I’m also just skeptical of hype around various stuff. After reading these forums as well as a number of really helpful articles and posts by @Randy Holmes-Farley and others, I tried bumping up the Alk by about .75 dKh using baking soda. I understand there is some evidence that boosting Alk can increase calcification.

I went slow and did the bump in two additions over two days. Result: Ca 430 ppm, Alk 7.7 dKh.

Well! Two days later, I’m reading Ca 410, Alk 7.1. I don’t think I’d be in abiotic precipitation territory, so I’m chalking (haha) it up to calcification boosted by the extra Alk.

Would folks agree?

I also added some zoas (first coral!) in that time, but it’s a small colony and I wouldn’t think they consume CaCO3 in any serious quantity at all.

 

[BeejReef]

That sounds like a pretty reasonable hypothesis. You're clearly well researched. You could test your theory by continuing to nudge up alkalinity and wait to see if you can detect a decrease in calcium. Probably would take several days to a week bc calcium levels vary much more slowly than alk.

Sorry you're on the struggle-bus regarding coraline. Hope this is your answer.
I have what seems like crazy (.9dkh) daily demand for a very young tank, but it sure doesn't seem to be going to my frags. I mean, they are doing ok. Still, I think 80+% is going to snail shells and coraline. Hippie snails and free love... hundreds now

 

[rmurken]

That sounds like a pretty reasonable hypothesis. You're clearly well researched. You could test your theory by continuing to nudge up alkalinity and wait to see if you can detect a decrease in calcium. Probably would take several days to a week bc calcium levels vary much more slowly than alk.

Sorry you're on the struggle-bus regarding coraline. Hope this is your answer.
I have what seems like crazy (.9dkh) daily demand for a very young tank, but it sure doesn't seem to be going to my frags. I mean, they are doing ok. Still, I think 80+% is going to snail shells and coraline. Hippie snails and free love... hundreds now

Whoah snails! I have a handful of turbos and margaritas, but neither species seems to enjoy much of a love life in my tank. I have an urchin and a conch, and thousands of tiny spirobids. I have a hunch that the spirobids account for much of the demand. They may be the ones with the love lives.

I’ll do my WC this weekend, see where my levels are. Depending on that, I’ll either do more baking soda, or if Ca is still correspondingly low, my project will be to figure out if I can boost Ca/Alk with some kalk. If that would require too much water relative to my salinity and evaporation, then I’ll whip up some two-part.

Edit: I can get from where I am to 7.8 Alk and 415 or so Ca with about 1.1L of saturated kalk. I can add that over a day or so without throwing off my salinity enough to matter. But I’m starting to see why two-part is easier—less complicated to dose.

 

[BeejReef]

Kalk will easily satisfy your alk/calc demand for the foreseeable future. It is a little tricky if depending on evap top off or ato to dose it.

Im a 65g DT and will be able to keep up with 1.5 dkh daily alk demand w my evaporation.

Can't argue w 2 part though. If I had it to do over... Maybe. I broke down and got a bluetooth single head doser and dose saturated kalk out of a separate reservoir from my rodi/ato.

I like it. Can do w testing and adjusting magnesium every 3 or 4 weeks. My calcium tracks perfectly. Can predict it 95% once I know alk. Barely test it.

I'm noobly too though, so do your own research. Best of luck.

 

[rmurken]

Noobs unite! I have a fair amount of FW experience, but love the chemistry of SW. Also the diversity of livestock.

I have a batch of kalk settling and will use that. I think I like the two-part approach better and will whip up some of Randy’s formula and look to get into a predictable pattern like you. Besides, my ATO and sump situation need work; not the best setup for dripping kalk.

 

[rmurken]

Well I think my hypothesis is at least partially falsified. I think the low Ca reading was probably error. I did two tests today and got 435 and 440. I haven’t changed, added, or removed anything since yesterday so there’s no reason Ca would jump like that. But my Alk readings were consistent at about 7.1.

So no kalk. Just a WC and an adjustment of Alk up to 8 or so. I think with my current Ca level of 440ish, the balanced Alk level is somewhat higher than that even, but don’t see a reason to push it right now.