What went wrong—multiple choice question

[Mark Spencer]

Two months ago almost everything was great in my tank. Ca was 450, pH 8.3 and alkalinity just a little low at 7 dKH. These parameters were stable for over a year. Then, less than a month ago they changed dramatically. In particular, Ca has steadily decreased to 380 last week and to 340 today. This in spite of my adding turbo calcium (CaCl2). For the first time I am also noticing a growing hair algae population. I know I have changed several things but I'm not sure which is responsible.

These are the changes that have occured:
1. I have always replaced all make-up water with limewater. About 2 months ago I switched from ESV kalkwasser to Mrs. Wages pickling lime. I was shocked by the brown solution that resulted from the Mrs. Wages mixture.
2. I tried to increase the alkalinity by adding 2 teaspoons of baking soda per day. My dKH has risen from 7 to 8.
3. The bio load is slightly higher as my few pieces of SPS and LPS corals have grown nicely. I would guess that the Calcium demand has increased no more than 10%.
4. I have added a half teaspoon of turbo calcium every day for the last week but the Ca level has continued to plummet.
5. Three months ago I switched from Instant Ocean to Oceanic. I have since read many posts bemoaning the low alkalinity of this salt.

I am temporarily out of a Mg test kit so I can't say what that is now but I did supplement with Mg. I expect to have a new Mg test by week's end.
Which of the above, if any, might be responsible for the Ca demise.

[Randy Holmes-Farley]

I tried to increase the alkalinity by adding 2 teaspoons of baking soda per day. My dKH has risen from 7 to 8.


That is likely what drove the calcium down. You supplemented alkalinity and not calcium, and the only export route for alkalinity is precipitation of calcium carbonate. So calcium dropped.

If you are going to add that much baking soda, you'll need to add more calcium.

My suggestion is to make a balanced two part system out of the baking soda and the calcium chloride to ensure that you don't get off track of balanced dosing. This article explains how:

A Homemade Two-Part Calcium and Alkalinity Additive System
http://www.advancedaquarist.com/issu...l2004/chem.htm

[Mark Spencer]

As always, Randy, you are always there with the answer. Thanks again.
You may remember that I had posted a thread several weeks ago about chronically low alkalinity and that I came away with the epiphany that alkalinity's greatest role is supplying the carbonate concentration needed to bring the molar ratio of Ca to CO3 to 1:1 (rather than moderating the pH swings).
May I assume then that the drop in Ca is actually an indication that more Ca is now being metabolized by the coral whereas before there was a deficit of CO3 that prevented the Ca uptake?
I have been performing a sort-of-poor-man's two part addition of CaCl2 and baking soda for the last week but doing so by mixing up daily amounts every morning. Perhaps I need to wait longer and increase the amount of turbo calcium since, so far, the Ca continues to drop. How long before I should see an increase?
Lastly, and most importantly...I am now dosing limewater daily AND adding baking soda daily AND adding calcium daily. At this point might it make sense to just get a calcium reactor and save myself a lot of work?
Thanks as always,
Mark

[RustySnail]

Originally posted by Mark Spencer
May I assume then that the drop in Ca is actually an indication that more Ca is now being metabolized by the coral whereas before there was a deficit of CO3 that prevented the Ca uptake?

Yep... So long as you are not seeing huge amounts of precipitation onto pumps/plumbing. Once corals start getting a constant/stable supply of Alk/Ca they really start growing like weeds

Lastly, and most importantly...I am now dosing limewater daily AND adding baking soda daily AND adding calcium daily. At this point might it make sense to just get a calcium reactor and save myself a lot of work?

I'm doing the same currently; if you want you can switch to a Ca reactor or just keep dosing A/B via Randy's homebrew. I'm getting ready to switch over to Ca reactor but I will keep the limewater going to maintain good pH levels. Without limewater my tank will drift down to 7.8-7.9 pH and with the reactor alone I think it would be way too low. Constant limewater drip keeps my pH between 8.1 and 8.3; so adding Ca reactor in addition might be OK so long as the pH is not pushed too low.

Check your Magnesium level; might be low and causing too much abiotic precipitation of CaCO3 in your system.

[Randy Holmes-Farley]

May I assume then that the drop in Ca is actually an indication that more Ca is now being metabolized by the coral whereas before there was a deficit of CO3 that prevented the Ca uptake?

Probably. Coral calcification rates often speed up when alkalinity is raised from 7 to 11 dKH.

However, not all demand necessarily goes into organisms. There is also abiotic (nonbiological) precipitation of CaCO3 in reef aquarium. On pumps, heaters, substrate, etc.

Lastly, and most importantly...I am now dosing limewater daily AND adding baking soda daily AND adding calcium daily. At this point might it make sense to just get a calcium reactor and save myself a lot of work?


Maybe. Is the limewater maxed out?

[ostrow]

I'd also consider the Oceanic salt as a problem.

[Mark Spencer]

Thanks for the responses. I'll post in a week with the latest Ca and dKH readings.
Mark

[Randy Holmes-Farley]

You're welcome.

Good luck.

[Mark Spencer]

As promised.... one week later:
I switched over from Mrs. Wages lime to ESV brand. There is a definite difference in purity as ESV mixes up clean, white and leaves little residue whereas Mrs. Wages gives a light brown mixture and brown sediment. I haven't seen a big decrease in my new hair algae population so I don't think this change has made a difference. I am nonetheless concerned with the lower purity of Mrs. Wages lime.
I am dosing one heaping teaspoon of baking soda and one level teaspoon of turbo calcium (CaCl2) every day (total aquarium volume approximately 150 gal). My Ca concentration has leveled off at 370 +/- 20 ppm and my alkalinity at 8.5 +/- 1 dKH. This is in conjunction to the 2 gallons per day of saturated limewater dripped in nightly.
I realize now that the big advantage to a Ca reactor is that it supplies CO3 to the system and should eliminate the need for baking soda to increase the alkalinity.

[Randy Holmes-Farley]

I realize now that the big advantage to a Ca reactor is that it supplies CO3 to the system and should eliminate the need for baking soda to increase the alkalinity.

That need is because you are not adding enough limewater to meet the demand at that higher alkalinity. FWIW, both CaCO3/CO2 reactors and limewater add calcium and alkalinity in the same ratio (or close to it). So it is not so much what is being added as how much of it (recognizing also that limewater can be limited by evaporation).

[RustySnail]

Originally posted by Mark Spencer
I am dosing one heaping teaspoon of baking soda and one level teaspoon of turbo calcium (CaCl2) every day (total aquarium volume approximately 150 gal). My Ca concentration has leveled off at 370 +/- 20 ppm and my alkalinity at 8.5 +/- 1 dKH. This is in conjunction to the 2 gallons per day of saturated limewater dripped in nightly.

Sounds like you are maxed out on Ca/Alk addition via limewater; the added Baking Soda and TurboCa is the additional needed to keep levels stable. You might consider mixing up the A/B that Randy developed for Ca/Alk maintenance. I recently went from the limewater & A/B additions to a Ca reactor; but I'm still adding limewater at about 2.5 gallons/day to keep pH above 8.0 and Ca/Alk levels stable.

[wasp9166]

i also noticed mrs wages making a brown solution of late, didnt do it the first batch i bought.................

[Mark Spencer]

The solution from Mrs. Wages was so brown that I have stopped using it. There is no question that it has a lot of impurities. The only question is what these impurities are (and do they make a difference). There are a lot of Mrs. Wages afficionados out there so either Mrs. Wages recently changed or the impurities aren't an issue. My Ca is alkalinity have leveled off at 380 and 8-9, respectively so I suppose my calcium load from the SPS, LPS and coralline algae are consuming both as fast as I am supplying them.

[wasp9166]

the first batch i bought was in paper bags, this is in a new plastic container, it definitely did not leave a brown sludge on the bottom of my container like it does now, i think its time to change..............randy, would esv kalk be the way to go? or does the brand not matter? just the price?

[Randy Holmes-Farley]

I'd probably avoid lime that turned brown when mixed with water, but be sure it isn't your own water that contributes the color.

[wasp9166]

yeah i was thinking of that, i am on 13 months on the same membrane and di, meter still says 0 so i should be ok, my tap is 30..................ill get some esv, see what happens

[Mark Spencer]

Quite sure my water is good. I switched back to ESV lime and the solution is colorless and leaves very little residue. My Ca jumped up to 400 from 350 after 2 weeks of switching but its impossible to say for certain that the switch in lime is responsible.

[Randy Holmes-Farley]

Yes, that sounds like there was an issue with that batch of lime.