Calcium question

edwardlmarshall · #1 08/12/2002, 07:14 AM

Ok - I've read your calcium/alkalinity article along with many other accounts, but I still need some advice. I am using Salifert test kits. My Ca levels seem to remain at 240-260 ppm regardless of what I do. Here are my other relevant parameters, on average: SG: 1.026, Temp: 80, night ph: 8.2, day pH: 8.35, Alk: 4.2 meq/l, Mg 1400 ppm, no NO3/PO4.

I have tried dosing with CaOH but it doesn't seem to raise my Ca as much as it raises my Alk (over 5 meq/l). I have also tried dosing Kent Tech CB and liquid Ca without much effect. Am I using a bad test kit here (my former Seatest kit had always reported 400-450 ppm Ca)? Am I not being patient enough (I have been using the Salifert kit for 3 weeks)? Or is this a saturation situation like in your article?

FYI, I have good coralline growth and my frogspawn has maintained good growth. I also have a tridacna claim which I assume is using alot of Ca.

Bottom line: am I worrying needlessly or do I need to find a new method for keeping my Ca levels up? Thanks in advance for your opinion.

edwardlmarshall · #2 08/12/2002, 07:17 AM

I originally thought it was my Mg levels that were keeping Ca low. When I started testing, Mg was 1200 ppm. I have since raised that number to around 1400, but Ca did not change significantly.

Randy Holmes-Farley · #3 08/12/2002, 08:35 AM

Your calcium is low (assuming the test is correct) and the alkalinity is at the high end of normal (2.5 to 4 meq/L, IMO). Consequently, you cannot raise the calcium with a balanced additive of any type because it will push the alk too high, and just cause precipitation of calcium carbonate, resulting in nothing useful happening.

I'd suggest adding calcium chloride in substantial amounts (like the liquid calcium or turbo calcium). That large amount may surprise you. Use Andy's calculator to tell how much you'll need:

http://www.andy-hipkiss.co.uk/index....cacalc.htm</a>

FWIW, if the calcium is really that low, calcification will be reduced in corals. I'd suggest raising it to about 410 ppm.

edwardlmarshall · #4 08/12/2002, 01:49 PM

Thanks - your reply makes perfect sense! I hadn't considered that a "balanced" calcum additive would not necessarily help an "unbalanced" situation.

Randy Holmes-Farley · #5 08/12/2002, 02:05 PM

You're welcome!

andy-hipkiss · #6 08/13/2002, 08:21 AM

Oh blush.

Slight correction on the URL it should be http://www.andy-hipkiss.co.uk/cacalc.htm . It seems that the BB software here gets confused with the full URL (which includes a bit of javascript to ensure that the page is displayed with the menu structure correctly)

Randy Holmes-Farley · #7 08/13/2002, 08:58 AM

Thanks, Andy!