low alk

[mehdijenny]

hi to all
I have a 77g reef tank.
its contents :
one 4" yellow tang
one 4" clark's clown
one 2" clark's clown
one 2" bangai cardinal
2 big colt coral
1 big devil hand coral
1 medium gorgonia
1 small red flower tree(NPS)
1 big long tentacle anemone
large amount of coralline algae
Water parameters :
ph:8.1-8.2
kh:9
ca:480
mg:1380
po:0
ammo:0
nitrite:0
nitrate:0
temp:77-79
salinity: 1.025
calcium reactor filled with 1 part neo mag(dolomite) and 7 part coralazarus(aragonite)

recently I faced to a problem. my calcium reactor was brocken and fixing process get 2 days long. in this time my calcium didnt changed but alk dropped to 5.
after starting the calcium reactor problem solved but I test the water many times and find that alk use very fast but ca almost stable.
result: by working calcium reactor in a period ca go very high but alk not.
I want to know why this happen, Im sure that alk use by live stocks and not settle.
please guide me what should I do. I think solve this problem by adding some ca user to my tank, is this a good way ? and if it is recommend me that species.
other way that I think may helpful is to increase dolomite media in calcium reactor and decreas aragonite.
excuse me for my bad english

[Randy Holmes-Farley]

hi to all


recently I faced to a problem. my calcium reactor was brocken and fixing process get 2 days long. in this time my calcium didnt changed but alk dropped to 5.
after starting the calcium reactor problem solved but I test the water many times and find that alk use very fast but ca almost stable.
result: by working calcium reactor in a period ca go very high but alk not.
I want to know why this happen, Im sure that alk use by live stocks and not settle.

The first part is normal.

If you are at 9 dKH and 440 ppm calcium, and let corals and such use what they will without supplements, alkalinity will decline to 7 dKH but calcium will still be about 427 ppm, which is not much of an observable drop at all. That is due to the mathematics of calcium carbonate formation: 2.8 dKH for each 18-20 ppm of calcium.

Turning it back on, there is no way that calcium can rise substantially without alk rising. So there must be some testing error involved somewhere. There is just no process to boost calcium and not alkalinity with a reactor of dolomite and aragonite.

You added nothing else?

[mehdijenny]

The first part is normal.

If you are at 9 dKH and 440 ppm calcium, and let corals and such use what they will without supplements, alkalinity will decline to 7 dKH but calcium will still be about 427 ppm, which is not much of an observable drop at all. That is due to the mathematics of calcium carbonate formation: 2.8 dKH for each 18-20 ppm of calcium.

Turning it back on, there is no way that calcium can rise substantially without alk rising. So there must be some testing error involved somewhere. There is just no process to boost calcium and not alkalinity with a reactor of dolomite and aragonite.

You added nothing else?

you right at all, its my wrong to not explain exactly
my meaning of CALCIUM ALMOST STABLE was its change very low Compared with alk. I think it is uncommon to alk drop from 9 to 5 in just two days because in past that I had not calcium reactor and I used triple buffer(tropic marine) when I added buffer and get alk to 10 it take 3 weeks to dropped to 6.
also I didnt add any other thing that related to alk,ca,mg.

2 month ago I dose kalkwasser and for short time ca get to 500 and alk 4 :eek1:
some times I really amazed about my tank and happened events because they dont following any chemistry rules.

but second way I suggested:
when I fill calcium reactor with aragonite completly outgoing water has 13 dkh but when filled with dolomite completly outgoing water has 24 dkh

after all of these what should I do ?
in this situation if any thing happen to my calcium reactor, befor I can fix it my alk drop and live stocks shocked. and from the other hand overdose of calcium over the time is still exist.
Can calcium user corals (more calcium and less alk) solve this issue in your mind ?

[Randy Holmes-Farley]

I'm confused. With the reactor back on what is the aquarium calcium and alkalinity?

Corals use calcium and alkallinity in roughly the same ratio they are added by an aragonite reactor.

I'd be careful with the dolomote in the reactor. Just a little is all it takes. The dolomote is adding a lot of alkalinity (more than aragonite) for each unit of calcium because a lot of what is dissolving is magnesium carbonate.

[mehdijenny]

is it possible cause of unbalance cal/alk is high amount of mg or sr ?
I read an article about alk. that explain how alk deplete during nitrogen cycle but in that was expressed when nitrate be 50 or higher this happen.
in your mind if my calcium reactor work continuously cal go up to what number ? does this cal raise stop ?
and if I add alk buffer and make alk and cal balance after that does calcium reactor raise these two balanced ?

[bertoni]

The magnesium level won't affect the calcium or alkalinity unless it's very, very low, in which case, the tank might see more precipitation. The strontium level could only be an issue if it was grossly overdosed.

[Randy Holmes-Farley]

in your mind if my calcium reactor work continuously cal go up to what number ? does this cal raise stop ?
and if I add alk buffer and make alk and cal balance after that does calcium reactor raise these two balanced ?

The reactor as you have it adds a bit more than 2.8 dKH of alkalinity for each 20 ppm of calcium, so if you boosted calcium by 40 ppm using it, you'd necessarily boost alkalinity too high.

[mehdijenny]

The reactor as you have it adds a bit more than 2.8 dKH of alkalinity for each 20 ppm of calcium, so if you boosted calcium by 40 ppm using it, you'd necessarily boost alkalinity too high.

excuse me I couldn't get your meaning. please explain more.

[Randy Holmes-Farley]

As aragonite dissolves in the reactor, it will add 2.8 dKH of alkalinity for each 20 ppm of calcium added to the aquarium.

For that reason, you cannot use this reactor to make calcium do up by 40 ppm because alkalinity will increase by 5.6 dKH to 5.6 + 9 dKh = 14.6 dKH.

Does that make sense?

[mehdijenny]

I know this discusstion become boring for you but I really need experienced people support.
I think you got my meaning wrong I dont want to raise cal I want to raise alk and stop raising cal and also decrease cal amount.
I cant check my water chemistry regularly because Im college student in another city that my tank placed there, for this reason I plan to make situation stable for minimum 15 days that I could travel to my home town and inspect to my tank.
exactly I need to calculate cal/alk use of my tank and add these two parameter balance by calcium reactor.(my target is cal: 450 & alk: 11)
maybe I should attain this by find a suitable mix of aragonite and dolomite instead of 9:1.
Are you accept with me ? Otherwise advise me better way .

[Randy Holmes-Farley]

The best way to determine how to set the reactor is by trial and error through monitoring the alkalinity level in the aquarium. DO NOT control or adjust it based on calcium readings.

If calcium is low after you get the alkalinity staying where you want it, you can manually add a corrective dose of calcium chloride.

Is your reactor controlled by a pH controller and solenoid on the CO2 source, or by a needle valve on the CO2?

[mehdijenny]

after I get the alk staying where I want(refere to your explanations)
If calcium is high! so then what should I do ?
I use to control co2 by needle valve

[Randy Holmes-Farley]

It should not be, but if it is, you have two options. Switch to using a normal calcium salt mix (not one that has calcium at 500 ppm) for water changes (which will bring it down), or you can use an alkalinity supplement for a while and not supplement calcium and it will decline. :)

[mehdijenny]

so if I do these and make alk and cal balance for once, after this by working calcium reactor over the time will these two parameters become imbalanced again? or they will stay balanced without adding buffer or changing water ?
the salt I use is red sea. calcium: 450- mg: 1340- alk: 12
Although I do not water change generaly(maybe 10% every month or less)

[bertoni]

The parameters should stay at a relatively fixed ratio for a long period of time, if you keep the alkalinity at the same level. There are some processes that will affect the ratio:

http://reefkeeping.com/issues/2004-12/rhf/index.htm

They tend to have a small effect, though. Magnesium consumption and supplementation can be another issue, as well.