Mag, Cal, Alk question

[wla1610]

Can anyone tell me what the relationship of Calcium, Magnesium, and Alkalinity in a tank?
I have a 46 gal tank with the following corals and fish
384W PC lighting - 3 month old bulbs
Frogspawn
Hammer Coral
Toadstool Mushroom
Bubble Coral
2 Yuma mushrooms
Red & Blue Mushrooms
Xenia
2 Gold Stripe Maroon Clowns + GBTA
Coral Beauty
Purple Firefish
Purple Psuedo
Yellow Tang *small
My calcium is at 400-420 ppm - which is a bit low
Alk is at 7.7dkh - a bit low
Mag - no idea. A friend is ordering a kit for me.
Ph - ~8.2
Ammonia, Nitrite, Nitrate - 0
I have some warner marine calcium and magnesium supplements. I'm hesitant to add mag since i have no idea what level my magnesium level is. I've been adding 1 Tsp of Cal every couple days to try to keep my Cal up.

 

[weberian]

I've read you need a certain level of magnesium in order for the water to absorb calcium. So I went ahead and ordered the salifert mag test kit. My magnesium was fine, around 1400. What I read about mag came off the side of Kent's buffer or liq. calcium bottles. I was worried about the mag level because I had not done a water change in quite some time. But my mag level was fine - I only have one coral yellow polyps. My problem turned out to be not enough fresh air / oxygen in the room, because it's in the cellar where our furnace is.

 

[azocean709]

IMO your calcium is right on the money....If you keep raising your calcium it will throw off your Alk. PH ALK AND CALCIUM work together. they will all affect each other. and if you have no clams and SPS corals, really high calcium in not really necessary.400 to 450 is a good number. your mag should be between 1250 and 1350. DONT suppliment mag if you don't know what the level is...Too much mag can be a nasty thing in your tank, just like Elemental Iodine. don't ever dose anything if you know.... That will just cause you problems...and cause your creatures problems. Like dying.

 

[wla1610]

Ok thanks for the replies. I don't want to add anything I can't test. The reason I'm worried about my calcium is because I've been having alot of coraline turning white. My toadstool mushroom has a patch of its tentacles that turned pale almost white. I've read that 400-420 is still a bit low for calcium. I'd feel better if it was a little higher personally. I'll just have to keep testing.
In the last month I've added most of these corals. I need to figure out how much calcium I'm going through in a week so I know if I need to add extra. I'll have to get back to my once a week water changes. I usually do 5 gal a week.
I hope this all stablizes soon. Everything was well until I started adding in my corals.

 

[clown52]

How do you get your Calcuim down? Mine always tests high, can that be a bad thing?

 

[wla1610]

Not sure on how to get it down. Check your water when you mix it. You could have a bad batch of salt possibly?
I had that issue when I first started this hobby.
Also, in response to the oxygen level. Does skimming help with the oxygen in the water? I really have my skimmer open for a wetter skim in hope that I will also get more oxygen in my water.

 

[azocean709]

skimming does help your oxygen. i dry skim myself...less waste of seawater that way with same effect.. I don't know your exact set up of filtration, but surface movement, water flowing out of an overflow box down the rippled blue tubing, water going over baffles in a refugium, all that creates oxygenation in the water. im sure there is someone that can explain it better than I , but there are good threads on it. I do know that good water movement creats it...My 55 gallon with 30 gallon fuge has roughly a 22X turn over rate of my water. which is pretty good to put oxygen in the water. do a search lots of info on it here.

 

[azocean709]

also i meant to add, my coraline turns slightly white when it is growing. Now a buttload of coraline will eat up calcium, thus having to supliment...my levels generally stay between 450 and 475, I drip kalk also the 400 to 420 is what is says good levels are on the back of the test box. I do what ever it takes for good growth and proper balance of my water quality.