Alkalinity chemistry question.

DannyB · Jan 13, 2016

So my calcium and Magnesium are high. Calcium 500 and Magnesium 1500.

My alkalinity on the other hand is 130ppm on Hanna.

I never dose Magnesium and was only dosing Calcium through Kalk with my ATO.

The Kalk kept my Alk steady but my Calcium always rose, hence it is high now. I have stopped running Kalk now and have been looking into using 2 part which from BRS's website says it needs to be dosed 1:1 Ca Alk. If i do this, the Ca will continue to rise? Is my tank being starved of Alk and therefore not using Ca? I don't seem to get much growth out of my sps and coraline algae is not really growing either.

Am i missing something or doing something wrong? I am running zeovit and was told to keep the alk at a lower level when using zeo but it being low seems to inhibiting growth as well.

I am sure I have not provided enough information so let me know what other information I need to provide.

Thanks for any assistance.

biom · Jan 13, 2016

What is salinity and how do you measure it? Very often when calcium and (or) magnesium are high without dosing is question of high salinity.
Do you run full zeo? stones etc.

Cory · Jan 13, 2016

Your alkalinity is 7.28dkh. Id be curious of po4, as thats the most growth limiting thing when alk and calcium are normal. Whats po4?

Randy Holmes-Farley · Jan 13, 2016

The use of limewater long term tends to make calcium rise if you use it to maintain alkalinity. I have experienced that. That is because it has a fixed ratio of calcium to alkalinity, but in a tank where it is being used, magnesium slips into crystals of calcium carbonate in place of some calcium, leaving some calcium out. In general, calcium at 550 ppm is no concern. Some salt mixes start that high or higher.

In terms of alk, 130 ppm (7.3 dKH) is fine, but it is also fien to raise it if you want.

If you dose the two part as recommended, calcium will not rise except as you make alkalinity rise. If you want a one time correction to boost alk, just use the alk part. But for routine maintenance, use both and it will keep calcium steady. If you want to lower calcium, using just the alk part for a while is also fine.

DannyB · Jan 13, 2016

biom said:
What is salinity and how do you measure it? Very often when calcium and (or) magnesium are high without dosing is question of high salinity.
Do you run full zeo? stones etc.

My salinity is actually a bit low, 1.023. I measure by refractometer which is calibrated before each use. The salinity was my first thought as well. I do run full ZEo, stones, bak, start, food with a couple other products here and there.

DannyB · Jan 13, 2016

Cory said:
Your alkalinity is 7.28dkh. Id be curious of po4, as thats the most growth limiting thing when alk and calcium are normal. Whats po4?

My po4 was at 0.033ppm a few days ago, i have since changed my zeolites and it has gone down to 0.021 as of last night.

DannyB · Jan 13, 2016

Randy Holmes-Farley said:
The use of limewater long term tends to make calcium rise if you use it to maintain alkalinity. I have experienced that. That is because it has a fixed ratio of calcium to alkalinity, but in a tank where it is being used, magnesium slips into crystals of calcium carbonate in place of some calcium, leaving some calcium out. In general, calcium at 50 ppm is no concern. Some salt mixes start that high or higher.

In terms of alk, 130 ppm (7.3 dKH) is fine, but it is also fien to raise it if you want.

If you dose the two part as recommended, calcium will not rise except as you make alkalinity rise. If you want a one time correction to boost alk, just use the alk part. But for routine maintenance, use both and it will keep calcium steady. If you want to lower calcium, using just the alk part for a while is also fine.

I have been using limewater for a while but it seemed to get less consistent with the calcium creeping up, my salt mix, red sea coral pro, is high in calcium and magnesium.

I was planning on raising alk to 160ppm and wanting to maintain at that level.

Is the magnesium an issue being that high? I don't know the cons of high calcium and magnesium.

I should be fine dosing only alk until the calcium lowers a bit?