Dose for Higher Alk --get lower Calcium?

[sen5241b]

I'm seriously wondering if the low cal I've been seeing in just the last few months is of my own doing. Like 6 months ago I started trying to keep my alk higher than 7 --it was typically 7 and occasionally dropping to 6. My cal was always 450ppm and higher. Ever since I started dosing baking soda (UNbaked) my calcium has dropped a lot. I can't keep it above 400. Then I read this:

I suggest that aquarists maintain alkalinity between about 2.5 and 4 meq/L (7-11 dKH, 125-200 ppm CaCO3 equivalents), although higher levels are acceptable as long as they do not depress the calcium level.

Alkalinity levels above those in natural seawater increase the abiotic (nonbiological) precipitation of calcium carbonate on objects such as heaters and pump impellers. This precipitation not only wastes calcium and alkalinity that aquarists are carefully adding, but it also increases equipment maintenance requirements. When elevated alkalinity is driving this precipitation, it can also depress the calcium level. A raised alkalinity level can therefore create undesirable consequences.

Reef Aquarium Water Parameters by Randy Holmes-Farley - Reefkeeping.com

Is this why my cal has been low? I'm thinking multiple water changes and trying no dosing at all. If alk and cal drop anyways then just going to a Kalkwasser drip. What to do?

 

[tankedchemist]

I don't dose anything-- I prefer to use a high-quaoity salt and just do frequent water changes.

Are you seeing a white chalky buildup on any of your equipment that doesn't easily dissolve in water?

I've heard of people keeping their alk way high-- like 14-- and not havint precipitation. Also, it matters how much magnesium is in your system-- if you're low on Mg, it's easier for the calcium carbonate to precipitate.

It could also be that keeping your alk within a "normal" range has caused increased biological calcification, and that could be why your seeing a decrease in calcium. I believe that is why many people dose cal and alk at the same time.

 

[sen5241b]

Actually there is not a whole lot of white chalky buildup on the equipment.

 

[tankedchemist]

then I'd presume your coral/coralline/etc are just using up the calcium and carbonate. makes sense, really, if carbonate was their limiting reagent prior to you dosing.

 

[daugherty]

if you have a higher mag level you will be able to maintain higher levels of both alk and cal

 

[puttycat]

+1 James. Randy has info somewhere about that too. He says to mix epson salts in RO. test first to see if is low.