Can't maintain alk...

[kwirky]

I've got a bucket of oceanpure pro I'm using while I wait for reefer's best to come to Canada. Never had problems other than insanely high Mg levels.

the temperature I mixed my salt at made a difference. If I mixed salt up then warmed it to the required temperature it would precipitate alk. I was having calcium/alk problems at one point but I eventually figured out it was my own human error and the fact I was dosing home made 2 part at a single time during the day.

Dosing both chemicals all at once caused a great deal of it to precipitate and led to imballances. I found if I spread the two chemicals out to two doses (one morning, one evening) I had more reliable dosing. And I dosed the calcium and alk portions 30 minutes apart to prevent them from reacting with each other and preciptating. Plus I find the regiment of hand dosing 2 part introduced all sorts of little errors that made it hard to figure out what exactly was the cause of errors when they happened. I could never do it like clockwork.

[ed99]

I'm having the same problem, and I am also using Ocean Pure Pro salt. I wonder if this is part of the cause. I'm trying to maintain an alkalinity (KH) of between 7 and 8, and do this I have to add 3 heaping teaspoons of Seachem Reef Builder alkalinity booster every 2 days in a 200 gal aquarium. One thing I have noticed is that I lose about 0.5 of KH every day, so it is not an instantaneous reaction. Could it be that some carbonate minerals are precipitating out in that time frame?

My calcium levels have stayed high (425-450ppm) and magnesium levels are also high (1450-1500 ppm) at a salinity (SG) of 1.024. I tested a new batch of the salt and it gave me a [Ca2+] of 525 ppm and Kh of 9.5 at a salinity of 1.0255. By the way I am using Elos test kits.

Does this sound like an additive imbalance as well (I haven't added any Ca supplments)? I've mixed the additive in fresh water and never noticed much precipitate, but I must admit I didn't ensure every last bit was dissolved. However, the amount left was insignificant compared to what I started with.

Appreciate if anybody has some more insights- I have read a few of the Farley-Holmes articles and have a degree in chemistry so that part of the article is not a mystery, but it is not obvious to me where the carbonate is being consumed.

Mike- hope you don't mind my jumping in this thread- I just thought I'd post here since we're having some of the same problems.

Ed

[ed99]

By the way- Sean's point on the high Mg level is interesting. I wonder if that is enough to reduce the carbonate concentration? My Mg levels are only going up however. Guess I should do another test on the Ocean Pure salt.

[untamed]

Originally Posted by ed99

I'm having the same problem, and I am also using Ocean Pure Pro salt. I wonder if this is part of the cause. I'm trying to maintain an alkalinity (KH) of between 7 and 8, and do this I have to add 3 heaping teaspoons of Seachem Reef Builder alkalinity booster every 2 days in a 200 gal aquarium. One thing I have noticed is that I lose about 0.5 of KH every day, so it is not an instantaneous reaction. Could it be that some carbonate minerals are precipitating out in that time frame?

My calcium levels have stayed high (425-450ppm) and magnesium levels are also high (1450-1500 ppm) at a salinity (SG) of 1.024. I tested a new batch of the salt and it gave me a [Ca2+] of 525 ppm and Kh of 9.5 at a salinity of 1.0255. By the way I am using Elos test kits.

Ed

I assume that you are using some sort of balanced Ca/Alk supplement. Generally speaking...if you are measuring low Alk it probably means that you aren't adding enough of the balanced supplement. You might think that more balanced additive would drive BOTH Ca and Alk up...but it doesn't work quite like that.

Another way of saying the same thing...is if you are not adding enough balanced additive (ie: Ca Reacter running to low, or not enough Kalk, or not enough C-Balance etc....), you'll see low Alk before you see low Ca.

[ed99]

Originally Posted by untamed

I assume that you are using some sort of balanced Ca/Alk supplement. Generally speaking...if you are measuring low Alk it probably means that you aren't adding enough of the balanced supplement. You might think that more balanced additive would drive BOTH Ca and Alk up...but it doesn't work quite like that.

Another way of saying the same thing...is if you are not adding enough balanced additive (ie: Ca Reacter running to low, or not enough Kalk, or not enough C-Balance etc....), you'll see low Alk before you see low Ca.

I'm adding the Seachem Reef Builder which says it boosts alkalinity. I'm not sure what is in there, though it does mention there is some Ca amongst other cations. I have not seen [Ca] below 400 for months and it has come up t0 425-450 since I've gone hard on the alkalinity (I wasn't testing the alk for ages since I had never had trouble with it before).

If I'm not adding enough of the alk booster should I expect to see an immediate rise followed by the slow decline over the next two days? I don't have any SPS so I wouldn't expect to have such a high alkalinity demand in the tank.

I'm also wondering if I would be better off using washing soda or baking soda to get back to a better ratio of Ca to carbonate?

[MikeP]

It's sounding like it comes down to what you use to dose. I thought maybe it had more to do with other elements in the tank? Should I try to get the alk level up higher (like 11 or 12 dkh) and see how fast it comes down.

[kwirky]

try baked baking soda to raise alk. (sodium bicarbonate anhydroxide)
spread a thin (1/4" layer) of baking soda on a cookie sheet lined with tinfoil. Bake it in the oven at 400F for 2 hours. This drives the co2 out of the baking soda so that idoesn't lower your pH when you add it into the tank. It's ok to cook it at a higher temperature or for longer if you want to be sure.

Then use this calculator here to find out how much to add.

http://reef.diesyst.com/flashcalc/flashcalc.html

Tell it all your levels, your desired level of the parameter you want changed and what you're using to raise it. It'll tell you how much to add to raise your alk, and tell you the ballanced calcium for that alkalinity level.

For instance you have an alk of 7dkH, and you want 8.5dkH. You're using baked baking soda. Your total water volume is 100 gallons. You need to add 10.7 grams of the baked baking soda and your ballanced calcium level would be 420ppm.

(alk dosing should be done gradually to prevent pH spikes. Don't raise your pH more than 0.2 per day)

You'll have to keep on top of your dosing of 2 part afterwards otherwise your levels will just go outa whack again.

And here's an excellent article on making your own 2 part:
http://reefkeeping.com/issues/2006-02/rhf/index.php