Alk won't go over 5.5

[5ft24]

That's what's frustrating. I don't have anything that really uses CA. I have 2 frags of Zoa's, and no other corals. For over a year, the tank was nice and stable. Haven't changed salt, using Oceanic. It mixes up at 1.023 with 420Ca, 1250-1300Mg and 8.5-9 dKH.
I need to get my own better test kits, but the LFS showed 410Ca, 1500Mg and 5.5dKH...
Going to try a 20G water change this weekend... My 5g and 10g changes make a little difference, but then it drops back to 5.5 again... Grrrrr

Just to be clear, your alk is 5.5 dKH (1.8meq/l), not 5 meq/l (which is 14 dKH).

According to this 13 year old article, you are probably not meeting your calcium-carbonate demands, & you should just dose up both till you get where you want to be. IMO, setup a carx.

http://www.advancedaquarist.com/2002/11/chemistry

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[5ft24]

ahhhh then that means test kit is good.

At least able to read above 5.5

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[BeanMachine]

That's what's frustrating. I don't have anything that really uses CA. I have 2 frags of Zoa's, and no other corals. For over a year, the tank was nice and stable. Haven't changed salt, using Oceanic. It mixes up at 1.023 with 420Ca, 1250-1300Mg and 8.5-9 dKH.
I need to get my own better test kits, but the LFS showed 410Ca, 1500Mg and 5.5dKH...
Going to try a 20G water change this weekend... My 5g and 10g changes make a little difference, but then it drops back to 5.5 again... Grrrrr





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You should consider sending in a Triton Water Test once you get proper test kits to verify your test results. While it isn't the cheapest thing in the world, it would be useful in your situation.

http://uniquecorals.com/dry-goods/triton/triton-labs-reef-aquarium-water-test-single-test-vials.html

 

[daddie05]

I had no idea Mg affected the Ca and Alk. I am gonna start dosing more frequently!

 

[mikejrice]

Magnesium is a fulcrum which calcium and alkalinity balance across. To allow calcium to be in solution, magnesium needs to be three times the level in your system which means magnesium at 1500 will allow calcium to be stable at least 500 and alkalinity should be able to move right along with it. That said 1500 ppm magnesium is at the top end of what you want in your system and I would not dose any more right now. In my opinion, it sounds like your carbonate/bicarbonate ratio is off which can sometimes be hard to flip back due to interactions between the big three (calcium, alkalinity and magnesium.) fortunately there's a product in Seachem's Aquavitro line called Balance which I've used to great affect in solving this issue. I would highly recommend it for you problem.


Michael Rice
Denver, Colorado

 

[mikejrice]

All that said, I wouldn't resolve to dose magnesium before your resolve to test for it.


Michael Rice
Denver, Colorado