Cal/Mag/Alk Where to start?

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Magma

Aquarium Advice Freak
Joined
Sep 29, 2010
Messages
339
Location
Calgary, Canada
Now that I have started to add a few SPS frags to my tank im wondering about checking Cal levels and how to go about raising them. I want it as simple and as easy as possible.

I have never checked or dosed for Cal before, I do my water changes and have always had some good growth on my corals (mind you it has been slower than people who dose and keep up with it).

Little info on the tank:
Approx 180gal water volume
Run Carbon and GFO through BRS Dual Media reactor
SWC 160 Skimmer
LED Lights
IO Salt (Not reef, just regular with purple lid, I plan to switch back to IO Reef at Christmas when it goes on sale)

Water Changes every 3-4 weeks (aprox 30gal of water)


Coral growth so far:
Zoas, Colt Coral, Acans, Mushrooms, Frogspawn all have shown noticeable growth within the few months of setup.

SPS growth/Change
Birdsnest went from Brown to greenish on the flesh, not much for polyp extension
Red Millie has gone from white to brownish green with visible polyp extension and starting to encrust the plug its mounted on
Pink poccillopora(I believe) has kept its pinkish tone, started to encrust the plugs and has very visible polyp extension.


I tried a cheap API Calcium test when I started in the hobby and to be honest it never worked, I think I ended up adding 60 drops of the stuff to the vial and the coral never changed. This kind of soured me on trying to keep it all in check, instead I just kept up with water changes and never had SPS corals.

So when starting out what you recommend for a beginner in this area, what kits to use for testing, whats the simplest solution for me all the while keeping it cost effective as I have a newborn which takes a lot of my tank time.


Thanks for any help/advice you can offer
 
You can keep your calc and Alk levels up by increasing your PWC rates. Those who do a minimum of 10% per week seem to get by with just that. But at 16% every 3-4 weeks, you'll need supplements, there is no way your calcium test was accurate.
Some basic chemistry.
Alkalanity (carbonates mainly) love to combine with calcium and precipitate out of solution. We don't want that. The carbonates form the seed of particle, and then calcium starts to build on that and eventually precipitate out of solution. You can curtail that by raising magnesium levels. They also build on the carbonate molecule, even if it already has calcium forming on it. Once magnesium bonds, nothing further can bond, slowing or stoping the precipitation process.
Corals absorb all 3 elements at different rates (different corals absorb them all differently) but it needs to be in solution (not pricipitated out of solution).
Raising calcium will increase the rate of precip, thereby lowering alk. Raising Alk will increase precip, lowering calcium. Raising magnesium will slow precip, allowing both calc and Alk to raise (if the suplements are there).
Calc levels above 400ppm have shown NO observable increase in growth rates (in lab tests) hence it is our target level. Alk above 11dKH has shown an increase in coral growth, but has also shown a significant increase in both precipitation (and lowered calc levels) and scale build up. A target dKH of 7-11 is recommended.

I am doing PWC of 16% every 2-3 weeks with a quality reef salt (aquavitro). I dose 60ml Kent part A (calcium) and 50ml part B (alk) every 5 days for my 110 gal, plus 40 ml Kent Magnesium every 4 days. This seems to work as all my corals (SPS, LPS, polyps and 'shrooms) are growing very well.
 
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