Another ph/ALK/Mag/Cal issue w/calc reactor

[winstew]

I have been pretty OCDish about recording my reef chemistry. I recently picked up a used Calc reactor to use so I didn't have to dose 2 part anymore. After my last water change I measured my water again:

SG 1.026 (refractormeter)
pH 8.2
Calc 320ppm
ALK 12.3dKh 4.40
Mag 1500 ppm

all tests with Salifert in date test kits.


The calcium seems a little low for Reef Crystals salt, but I waited probably a week after the water change to measure. I'm pretty sure my reactor is working properly. Its an automatic solenoid with milwakee pH probe. The probe is pretty consitant at 6.5 and i can here the solenoid click open and close every so often.

Question is why is calcium so low, why is alk so high? How can i make sure reactor is working. Should shut the reactor off and dose for a week with 2 part again and measure?

 

[bertoni]

The reactor adds calcium and alkalinity at a fixed ratio of 2.8 dKH per 20 ppm Ca, so you'll need to turn back the reactor to let alkalinity drop, and dose some calcium chloride to get that level up. Once that's done, you should be able to tune the reactor to keep the parameters stable.

You might want to get a second opinion on the test kits, since they do fail sometimes.

 

[HighlandReefer]

If your alk kit is correct, then you will want to turn the CO2 off until your alk drops down where you want it. You will want to set your reactor for maintaining your alk. You will need to bring your calcium up to your desired level using calcium chloride. You may have to supplement some additional calcium until your alk drops. If you try to raise you calcium level with the reactor it will result in even higher alk levels.

 

[winstew]

The two little fishies 2 part that I used to use has a calcium additive and a buffer correct? If I shut the reactor off, or turn the CO2 way down Can I just add the 1st stage to bring up calcium?

 

[bertoni]

Yes, that'll work perfectly; it's a fine calcium chloride supplement, although it's more expensive than other products.

 

[winstew]

well i figured I have it so I might as well use it up since it really won't be used that much after the reactor is setup and running correctly

 

[bertoni]

Works for me.

 

[winstew]

Thanks for the advice... hopefully it works

 

[winstew]

do you think when everything is back to normal i should just run the reactor when the MH are on?

 

[HighlandReefer]

I see Jonathan posted while I was typing. :lol:

 

[chuckreef]

When you get everything adjusted to the range you desire, run the reactor 24/7 to provide a very stable alkalinity at the desired level.

 

[StillerNat]

Mag acts as a fence to keep Ca and alk getting together and stopping them from precipitating out. best is to raise Mg to 1700 then bring up the alk and then Ca. once Mg and alk are in check it will be easier for you to keep your calcium in check cause your mg is high enough to keep them from precipitating.
a good way to raise Mg in your Ca reactor is by adding Dolomite to your reactor. add about 10% or 1 to 2 inches on the bottom. dolomite dissolves faster and therefore puts the Mg in the water faster to slow the Ca down to stabilize it.

 

[HighlandReefer]

I don't see any benefit from raising your mag level above the recommended range of 1250 to 1350 ppm. If your mag level is low, say below 1100 ppm, this can effect the rate of growth of calcifying organisms. One possible exception might be if you decide to raise your mag level to fight Bryopsis, which is experimental IMHO.

Randy goes into this in this article:

Magnesium in Reef Aquaria
http://www.advancedaquarist.com/issues/oct2003/chem.htm


From this article:

"Whatever supplement you choose, I’d suggest targeting the natural seawater concentration: 1285 ppm. For practical purposes, 1250-1350 ppm is fine. I would not suggest raising magnesium by more than 100 ppm per day. If you need to raise it by several hundred ppm, splitting the addition over several days will allow you to better home in on the target concentration, and might possibly allow the aquarium to deal with impurities that may come in with the supplement.

It has been suggested that adding dolomite to CaCO3/CO2 reactors can help with magnesium problems. Dolomite is a material that contains both magnesium and calcium carbonate. If dolomite is being added to the reactor to maintain existing appropriate magnesium levels against the continual depletion via calcification (for example, if the calcium carbonate being used is too low in magnesium to maintain adequate magnesium) then this is a fine approach.

However, this method is unsuitable if the goal is to raise magnesium levels. The problem is that for every magnesium ion released from the dolomite, 2 units of alkalinity are also released:

MgCO3 Mg++ + CO3--

Consequently, if one wants to raise magnesium by 100 ppm, the alkalinity will necessarily rise by 8.2 meq/L (23 dKH). The only way around this problem is to add a mineral acid (not vinegar) to the aquarium to reduce the alkalinity, and that may be more problematic than just adding magnesium in the first place."

 

[winstew]

Yea i wasn't really planning on dosing any Magnesium, I just mentioned it because I tested it and I got 1500... Which was from a previous successful attempt to eliminate Bryosis, as mentioned above.

 

[bertoni]

I would avoid raising magnesium over 1300 over so, unless you're desperately trying to kill Bryopsis.