shrinking alkalinity.....high calcium

[Hobster]

kyles,

Randys article:

http://www.advancedaquarist.com/issues/nov2002/chem.htm

shows the relationship. Appears you are in zone 4. (as was I )
It takes a while for the Ca to move in relation to the Alk.

[RQ]

Hi randy
about your question, i am talking about an aquarium, not a bucket of artificial see water. The one described in "current tanks".
I tried to rise alk adding baking soda but with the same results as Kyles. Not only my Kh returned to the previous levels but my Ca was 380 and after dosing b soda, dropped to 330 in three days. So i stopped to add baking soda and pointed toward Mg wich is my target now.
but i don t want to hijack the thread so i m going to sart a new one later .
Thank you

[Randy Holmes-Farley]

I tried to rise alk adding baking soda but with the same results as Kyles. Not only my Kh returned to the previous levels but my Ca was 380 and after dosing b soda, dropped to 330 in three days. So i stopped to add baking soda and pointed toward Mg wich is my target now.

Perhaps the tank organisms ae just using it as fast or faster than you are adding it?

[Randy Holmes-Farley]

Cagri:

so I decided to push the alk higher by adding kent's alk suplement(reef builder), I calculated that if I added 2 teaspoons it would raised the alk by 1 mq/l, when I did that it started snowing

You mean Kent Coral builder, or Sechem Reef Builder?

Adding Kent Coral Builder is different than adding baking soda, although not hugely different. Still, adding a lot at once is more likely to cause precipitation than is baking soda as it won't have the same pH reducing efffect as baking soda.

Do you know the pH of the mix before adding anything special? Some salt mixes have a very high pH that, if not brought down by aeration, will greatly increase the liklihood of precipitation of CaCO3, especially if you boost the alkalinity.

FWIW, I don't add anything to my salt mix (except water) prior to adding it to the tank.

[Randy Holmes-Farley]

klyes:

So it appears the CA is coming down slowly but the ALk is droping very fast in just days, yet jumps at the slightest adjustment.

Yes, that's exactly how it is supposed to be. Alkalinity whips around like a jet ski while calcium is more like a slow moving barge.

[kyles]

Randy,
Yes, that's exactly how it is supposed to be. Alkalinity whips around like a jet ski while calcium is more like a slow moving barge.
Well thank you for all your help, it appears thats the exact scenario my CA & ALK is doing.
I loose about 1-2 dkh per day even while adding about 1 tsp of b soda per day.
But finally my CA has dropped to about 440 ppm, and my
ALK was at about 8.0....PH at 8.1

I still think I'm going to switch back to IO, because I never had to deal with shrinking ALK and CA off the chart before. If anything, My kalkwasser kept both to acceptable levels, and once and a while I'd have to add just a bit of turbo CA.
I don't know, maybe I've just been adding (3) tsp of kalk per Gal was too much......I am going to use about 1 tsp and continue to monitor.

[Randy Holmes-Farley]

I use IO and haven't seen a good reason to switch to something else (although i certainly would with a good reason).

In normal calcification, the drop is 2.8 dKH of alkalinity (1 meq/L) for each 20 ppm of calcium.

[Sloth]

I hope I'm not repeating anything that was already asked, but -

If corals use calcium and carbonates in the ratio you just described,
would precipitation on heaters and pumps remove calcium and carbonates from the water in the same ratios?

Does that make sense?

[RQ]

Originally posted by Randy Holmes-Farley
I tried to rise alk adding baking soda but with the same results as Kyles. Not only my Kh returned to the previous levels but my Ca was 380 and after dosing b soda, dropped to 330 in three days. So i stopped to add baking soda and pointed toward Mg wich is my target now.

Perhaps the tank organisms ae just using it as fast or faster than you are adding it?

But if the Kh is consumed as fast by the organisms, how can you explain the sudden drop in Ca (from 380 to 330 in three days)?

[gtrestoration]

If corals use calcium and carbonates in the ratio you just described, would precipitation on heaters and pumps remove calcium and carbonates from the water in the same ratios?

I asked about 3 weeks ago and the answer was yes.

RQ,

From your profile you are dealing with a large volume of water.

To compare usage and additives... my system is 200 gallons.

I drip 3 gallons limewater daily.
Also needed daily to keep alk above 8.5 dKH and calcium above 400 is 650ml each of Randy's 2 part homemade supplement.

This seems like alot, but daily tests have confirmed the need.

I now use a LiterMiter lll to drip all three of these and the system is much more stable and I'm not freezing up my pumps so quickly. When I used the dose-by-hand method I could lock-up a pump in less than a month.

Steve U

[RQ]

gtrestoration:
I drip 2 gallons of limewater daily, and that is enough to keep Ca around 400. The problem i have is with alk because is very low now (between 4 and 5 dkh). When i try to rise it with baking soda, the Kh return to the previous levels after a few days and the Ca make a big drop. After that I continue adding limewater as usual and the Ca come back to 400 after a few days but de kh remain as low as before.

[Sloth]

I think your tank is just using a lot of Ca and a ton of alk. The alk is getting used as fast as you can replace it. Its "idling" down at the point were your corals are no longer able to suck it out of the water to use with calcium to form calcium carbonate skeletons.
That's my 2 cents

[gtrestoration]

RQ,

So that I understand.

How many gallons of water does this system hold?

When you have added baking soda in the past...
How much did you add?
How did you add it, as in mixed with fresh water, and where did you dump it, about how much water?
What is the pH of the system, high and low ranges.

What is the dKH you would like to maintain?

Steve U

[Randy Holmes-Farley]

If corals use calcium and carbonates in the ratio you just described,
would precipitation on heaters and pumps remove calcium and carbonates from the water in the same ratios?

Does that make sense?

Yes it makes sense, and yes, the ratio is the same. The only small differences have to do with the amount of magnesium and other ions that get into the calcium carbonate in place of either calcium or carbonate, which varuous between corals and between corals and abiotic precipitation.

[Randy Holmes-Farley]

But if the Kh is consumed as fast by the organisms, how can you explain the sudden drop in Ca (from 380 to 330 in three days)?

If the alkalinity dropped by2.5 meq/L (7 dKH), or you added enough baking soda to balance that, or a combiantion therof, that would be exactly right.

Sudden drops in calcium in the absence of any alkalinity supplements or alkalinity drop are either the result of testing error, or water changes with a salt mix with lower calcium.

[kyles]

RQ,
In plain english, If you add any ALK supplement (B. Soda) then CA will ALWAYS drop.
If you Add ank CA supplement (Turbo CA) then ALK will ALWAYS drop.
The only time they won't drop is if you add a BALANCED additive.
I know it's weird sounding but that's how it is. And that's why we are always dosing balanced additives like KALKWASSER.
My problem is I get lost in the mix of things when I am adding balance additives, and one or the other drops.
If I were you, trying to raise ALK and not lower CA, is to add I would add some Turbo Calcium at the same time that you add your B. soda, that way you keep your CA from droping.

With 500 Gals, You might try adding 6 tsp of B.soda with 3 tsp of Turbo CA, keep dripping kalkwasser, and check parameters the next day and dose again if need be.

[kyles]

How much Kalk to you all use per Gallon of water?
I was using 3 tsp per gal, and dripping 1/2 g per day.

[Randy Holmes-Farley]

If you add any ALK supplement (B. Soda) then CA will ALWAYS drop.


It will always eventually drop when the alkalinity is used up in calcification. Some folks might interpret that sentence to mean that it drops right away, which it may not always do.

[RQ]

Thank you all for your comments. I will try to answer each one of them.
Sloth:
i didn t see any special gowth in my hard corals skeletons on the time (between three days and a week) were the KH is consumed, and when i stop to add baking soda, the system is in balance at KH 4,5 and Ca 400. Because of that, i suspect that the problem is not related with coral using the alk but with some chemical reaction in the water.
gtrestoration:
The total volume of my system (two tanks plus sump) is 486 Us gallons, but i have a DSB with a plenum and several pounds of live rock so i would say that i have a water volume of 330 g.

I will give you a practical example of what is happen to my siystem:
june 5: Kh 4 - Ca 390 + 3 tbsp of baking soda mixed in 1/2 g of RODI fresh water and dumped in a strong current along the day.
June 5 end of the day readings: Kh 5 - Ca 380
june 6: Kh 4 + 3 tbsp more of baking soda.
june 7: Kh 5 - Ca 330
At this point, because of the low Ca i stopped to add b soda, and continued with the normal use of limewater.
june 11: Kh 4 - Ca 375.

The ph is 8,08 /8,14

My dream is 7 dkh but with 6 i will be extremly happy.

Randy: I tested Ca with salifert kit (i have two of them and the old messure like the new one), and Kh with salifert Kit and Sera Kit and they messure the same, so i don t think i have a testing problem, and i didn t change water during the example given above.

Kyles:
As far as i know, not always the Ca drop when you add baking soda. And certainly not at the ratio that dropped in the example i given above. But i m intrested in the solution that you propouse (add baking soda and Ca in a bigger proportion ). i would like to know the opinion of Randy about it.

[gtrestoration]

RQ,

It will take about 6 tsp to raise your 330 USG by 1 dKH. Your system can easily use that much dKH or more in one day.

If your system is using 2.8 dKH per day then it shoud also require 20ppm calcium be added. That would require about 16 tsp baking soda for dKH and 13 tsp calcium chloride for calcium.

Non of these figures are considering the limewater you are adding. I dose the same amount year round even though the evaporation changes. This way I need not adjust anything other than RO/DI makeup water.

What I did to resolve the usage issue on my system was to put together a log sheet and tested each twice per day for 3 weeks.

I logged
• Time
• pH
• dKH
• Number of tsp baking soda added
• Calcium ppm
• Number of teaspoons calcium Chloride added

I was rather surprised at the amount necessary twice daily. I took the results of those test and averaged the daily amount needed. Now I dose that average daily, and test weekly.

My estimates of the needed baking soda and calcium chloride come from...
http://www.kademani.com/reefchem.htm

Hope this helps.

Randy,
Hope I'm not out of line in your forum.

Steve U

[Randy Holmes-Farley]

Thanks, Steve,

And certainly not at the ratio that dropped in the example i given above.

I think that you are overinterpreting noise in the test kits. You dosed only alkalinity supplements, and the calcium declined. That's normal.

Then you added limewater and say calcium rose, but not alkalinity. That doesn't happen. Perhaps the 330 ppm calcium reading was wrong, and the value was just steadily dropping from about 390 ppm to 375 ppm calcium.

IMO, you do need to add more calcium and alkalinity supplements. My suggestion is to use some sort of balanced additive system so you need not worry about such changes on a day to day basis. These would include limewater, the two part systems, a CaCO3/CO2 reactor, etc.

[RQ]

Steve:
IThank you for your advice and for the link. Both very usefull.
Randy:
I apologize myself because i didn t explain the procedure well.
I never stopped to add limewater during the example given above. In this case you conclusions are the same?
Anyway i really appreciate your help. It is a real privilege for me to be able to communicate with someone with real knowledge in this area of our hobby.

[Randy Holmes-Farley]

I never stopped to add limewater during the example given above. In this case you conclusions are the same?

You never stopped adding it, or you never added it?

In any case, if you didn't add any calcium only supplements (like calcium chloride) or a mineral acid (like muriatic acid = hydrochloric acid) then the calcium cannot rise from 330 ppm to 375 ppm with no rise in alkalinity. If you used limewater for that rise, the alkalinity would jump by 2.25 meq/l (about 6.3 dKH).

Anyway i really appreciate your help.

You're welcome. That's what this forum is for!

[RQ]

Randy:
I never stopped adding limewater, and i didn t add any calcium only supplement or a mineral acid, but the calcium rose from 330 to 375 with no rise in alkalinity (on the contrary, the alk dropped). This is exactly my problem. i can t rise alk. without a drop in Ca levels, and when i reached the 400 Ca by the effects of limewater the alk returned to 4 dkh.
Could be any other cause for this, than a noise in the test kits?
Maybe some kind of acid from de DSB causing precipitation of alk?

[Randy Holmes-Farley]

I never stopped adding limewater, and i didn t add any calcium only supplement or a mineral acid, but the calcium rose from 330 to 375 with no rise in alkalinity (on the contrary, the alk dropped).

Then that is a measurement error, not a "'problem". There is no mechanism for that to happen that rapidly in the absence of calcium or acid additions (or a water change with off spec water).