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View Full Version : Alkalinity - PART 2 developed a black residue - Help anyone???


skydancer
06/09/2007, 08:27 PM
I just mixed 3 gallons of the part 2 supplement (Baking soda - 594 grams per 1 gal RODI water) and filled up my ALK container (picture to the right of the CA (dowflake - 500gr per 1 gal).
http://i126.photobucket.com/albums/p111/cubanbelicoso/Part2_Blackresidue-1.jpg

I have an Eheim 1048 on each container mixing the water. After about 3 hours the ALK part started developing this black residue.

It also did it last month on a much smaller scale and I thought the hi temp was "eating" up the mj1200 impeller and therefore the black residue. That's when I switched to the Eheims.
Can anybody shed any light on what this black mixture is?
Thank you in advance for your comments and help.

skydancer
06/09/2007, 08:43 PM
Correction... I shined a flash light thru the container and the "black residue" showed up as baking soda that is not dissolved!!!. I guess after I mixed it in the 1 gal milk jag and dumped it in the container for the hourly dosing, it settled again.
Is this normal?. Shouldn't it completely dissolve. Are my portions wrong? Will it dissolve over time?

BTW, the Ca part 1 looks milky and the dowflake is fully dissolved.

MrZ
06/09/2007, 09:15 PM
Did you bake the baking soda first? It's my understanding that baking the soda converts the sodium bicarbonate into sodium carbonate. Differences between the two include PH, solubility, and density. Solubility is the important one here. Recipe #1 calls for 594 grams of calcium carbonate (baked baking soda) while recipe #2 calls for 297 grams of calcium bicarbonate (unbaked baking soda) the difference in weight per gallon is because you won't get much more than that of either fully dissolved in pure water.

If you did bake the baking soda perhaps you didn't manage to bake it long enough or hot enough to fully convert it? The only other thing I can think of - if you are measuring it out by weight rather than volume, it is important to weigh out the baking soda before it is baked rather than after. It will lose weight as the extra carbon dioxide and water are removed forming a lighter compound - the sodium carbonate mentioned previously. You will be adding more than can be dissolved if you weigh it out after it is baked, and it won't properly match the part A calcium part either.

skydancer
06/09/2007, 09:28 PM
Oh Shoot...
I have never baked it in the 10 months I've been dosing it. I always thought it was optional, not a requirement.

Is there an updated article on the 2 part system method, on how hot and how long to bake it?

I must have mis-read the two recipes (#1 and #2).
So if I don't bake it I should use half as much? If so, why not always use half as much and not go thru the trouble of baking it? I'm sure there is an advantage in baking it, or people wouldn't do it...

MrZ
06/09/2007, 09:34 PM
Just checked my math in case my guess was right - assuming all sodium bicarbonate is converted into sodium carbonate you would be adding 58% more than called for if you made the rather easy mistake of weighing the soda after baking.

skydancer
06/09/2007, 10:23 PM
Back to the kitchen making desert... (baking the baking soda... for an hour in 300 deg - according to the recipe #1)

I guess I missed the instructions because it said "bake the baking soda" and at the time I thought I had bought it baked...!!! Heck, I don't know how I could've mis-read that!!!

Indeed though, the mixure had a tint of black and that's why the black cloud developed. I guess if the baking soda doesn't disolve it becomes dense and colorates to a light gray tint... FYI, everybody...

reefnetworth
06/09/2007, 11:05 PM
FWIW, if you mix it with warm water it disolves faster. :)
JDM :cool:

skydancer
06/10/2007, 12:02 PM
What a difference some good advise makes!!!.
Thanks MrZ. I baked the baking soda, and dissolved it in RODI and... success... My ALK dosing container is crystal clear, now... WOW. No more clogging the lines while dosing... I've been fighting this clogging issue for 10 months, NOT KNOWING THAT I WAS PREPARING THE MIX WHILE DOING SOMETHING WRONG!!!

Thanks again guys...

Billybeau1
06/10/2007, 12:14 PM
Just remember that the baked baking soda will raise your pH much much more than the unbaked. The unbaked can actually tend to temporarily lower pH.

You'll want to make sure not to affect your pH by more than .2 units at a time.

skydancer
06/10/2007, 01:24 PM
<a href=showthread.php?s=&postid=10114874#post10114874 target=_blank>Originally posted</a> by Billybeau1
Just remember that the baked baking soda will raise your pH much much more than the unbaked. The unbaked can actually tend to temporarily lower pH.

You'll want to make sure not to affect your pH by more than .2 units at a time.

I have an aquacontroller reef computer dosing it for 1 minute every hour, so I'll be monitoring it closesly. Thanks for the heads up.

Billybeau1
06/10/2007, 01:29 PM
:thumbsup: