Ideas are needed please!

Hi,

Another weird problem that I would appreciate any and all thought on please.

My Alk (dKH) is too low at 7 in the tank. I normally run it at 10-11. My dKH out of my reactor is 11, it is usually around 24. Usually as there is a correlation betweek Alk and Calcuum (Calcium Carbonate) that I assume if the dKH is ok... life is ok. I was gone for ~ 1 week, my last reading about 2 weeks ago dKH was ~10.

Test on Friday when I added a new C02 tank and noted very low Alk readings.

These findings makes no sense at all to me so I am asking for help please.




Current Tank Parameters;

• Calcium is reading 500
• Magnesium is reading 1450
• Alk (dKH) is 7 in the tank
• Alk (dKH) out of my reactor is 11
• pH: 8.3
• Nitrates: 0
• Phosphates: 0
• Ammonia: 0
• Salinity: 0.025
• Temp: 78-80
• Silicates: Not tested
• Iodine: Not tested

What's changed...

1 week ago: New C02 Tank (5lbs), this is when I noticed the issue so this is not related.

45 days ago: New Sicce Pumps, 1600 gph (replace defective Hydor 1400 gph pumps)

3 months ago: One (1), 60 gallon water change

6 months ago: One (1), 60 gallon water change

6 months ago: Switched to Instant Ocean, Reef Crystals (from Tropic Marin Reef Pro)

6-9 Months ago: Nothing


I have purchased another new API dKH test kit, no change so it's not the test kit. I verified the Calcium readings using two (2) kits, Salifert and Red Sea. I only have a Salifert kit for Magnesium but tested it three (3) times.

I had to lower the effluent output to reduce introduction of additional Calcium & Magnesium at the cost of again lowering the dKH. I can consider using sodium bicarbonate but something else is going on and before I start changing or adding anything I would like to ask for thoughts.

I'm going to re-calibrate my pH probe now (let you know if it was off).
I'm going to search on-line on how to create a sodium bicarbonate dKH calibrator, let you know what it reads (but should be OK).

I am baffled.... there must be something that's I'm missing OR not looking at correctly... any thoughts are appreciated for sure (please).

Sincerely,
Grumpy (John L)

Have your SPS and LPS been growing a lot lately? I notice severe dips in my ALK when I have a major growth spurt among my corals

Other than that - dunno - maybe do some water changes to get it back up, rather than dosing with baking soda?? What kind of salt do you use? I've used a few in the past that wreak havok on my ALK and PH .......

Ohh, and I forget - how big is your tank Grumpy??

Hi Estanoche,

No significant growth lately.

My tank is a 155 with a total volume of 190 gallons.

As noted above, I have been using Instant Ocean Reef Crystal salt. When I tested the salt directly, the dKH is around 13. Much higher than my current readings.

ha! when I read 13 I thought - wow, that seems really high, why isnt my tank that high! But, in googling the internet it seems 13 is a reliable, expected result.... so hmmmmmmmm

Where is it going?

I'm gonna go do more googling

aha! this makes sense - Chemistry And The Aquarium: Solving Calcium And Alkalinity Problems — Advanced Aquarist | Aquarist Magazine and Blog

"If, for example, you add too much of a calcium supplement, you will drive down alkalinity as you get precipitation of calcium carbonate in the tank. Likewise, adding too much of an alkalinity supplement can result in reduction of calcium. "

So, the low ALK could be related to the high CA, which caused the alk to precipitate - maybe you ran into an extremely strong section of CA in your reactor media???

When I saw the Calcium I thought it might have something to do with the Alk. It will correct itself when your corals use it up. 7 really isn't enough to be worried about. Mine stays pretty low all the time.

Estanoche, So I too have this article bookmarked, and read it no fewer than 3 times... for some reason I failed to take in the quote below... I thought this could be the result of calcium carbonate precipitation in the tank but fully expected the Alk to follow... not drop. I am re-reading each line carefully again (you know how you read stuff but miss stuff it at the same time... dang! ).

It still does not explain why the effluent is only 11 so the other thing I'm going to do is to fill my reactor, it's currently at about 1/4 full and then lower my effluent to just a few drops a minute and hope the calcium levels drop over the next week and also hope that the dKH does not... I'll let you know.

Thank you very much for your feedback, really appreciated.

rjrking, Thanks for confirming that a dKH reading of ~7 is OK. I really didn't want this to get out of control with huge swings in my dKH, thus my panic message. I am worried because a 35% change in any reading in the tank can't be good so I really wanted to better understand what the heck might be going on. I'm going to assume that the high calcium in the tank is responsible for the alk drop and by shuting things down for a few days everything wil bounce back.

Thanks Geeks!

Grumpy

Originally Posted by estanoche

aha! this makes sense - Chemistry And The Aquarium: Solving Calcium And Alkalinity Problems — Advanced Aquarist | Aquarist Magazine and Blog

"If, for example, you add too much of a calcium supplement, you will drive down alkalinity as you get precipitation of calcium carbonate in the tank. Likewise, adding too much of an alkalinity supplement can result in reduction of calcium. "

So, the low ALK could be related to the high CA, which caused the alk to precipitate - maybe you ran into an extremely strong section of CA in your reactor media???

Different reactor media can dissolve at different calcium to alk ratios, maybe something like that is causing the imbalance. Baking soda is always an easy fix too...

How old is the media in the reactor? Not to sound like an a**hole, but you kinda answered your own question here:

My dKH out of my reactor is 11, it is usually around 24.

The problem seems to be with the reactor, not your system. It you normally see 24dKh and now your only seeing 11dKh, then the problem lies with the Reactor system itself.
-pH probe out of calibration
-Media Exhausted
-Faulty Seleniod

Not stepping on toes here, but if the Alk had precipitated, there should have been signs in the tank (Snow storm, white blanket on the sand bed and covering corals). If it had gotten to the point of precipitation, I would think you should see coral stress (aka Alk burn). You would see it predominantly at the tips of SPS and LPS.

Also something to note (and this is why you wouldn't see precipitation), your Mag is within acceptable range. Mag is what holds both Cal and Alk in suspension (positive and negative ion attraction, but that's an entire other topic).

Your Calcium will drop over time since you shut the reactor down. It is a little high, but nothing to worry about since it will drop as it's used up. Alk at 7dKh is fine.

The articles on Reefkeeping website are excellent. RH Farley has some in-depth reads, but all are well worth it.

Figure out your reactor issue and your problem should be solved

Not stepping on any toes here.... Clearly the Calcium Reactor is the issue here there has never been a question about that. If you read back to my original post, the sudden Alk drop and trying to understand why the Calcium to Alk correlation is gone without significanat calcium carbonate precipitation which I just didn't understand what happened. I have since, completely rebuilt my reactor and with a water change I'm slowly getting things back in order.

What I have concluded is that when the reactor media is low (~1/3 full) and having the pH set too low (6.2'ish), there is a build of at the base of the reactor that somehow (still don't understand exactly why) inhibits the release of Alk but not Calcium or Magnesium, this is the only thing I can figure out what happened.

I understand that Calcium readings of 500 are high, but some consider it acceptable, I prefer to keep mine closer to 450 or so. I also understand the same is true with Mag at 1450. Please remember although some like a dKH of 7, I keep mine around 10 and when it suddenly dropped it sent off alarms.

All comments are appreciated, always.

Sincerely,
Grumpy

hmm that's odd that it's releasing one chemical and not the other. I'm about the worst at the chemistry part, so I won't try to help, but it seems like maybe the media would be the problem. Perhaps there was something off in it just a bit.

Hey rgrking... I too agree this is really weird and I've asked here and on other forums too, no one seems to have an explaination for why one and not the other.

I'm working to get things back in order, after refilling and cleaning the reactor I am getting greatly improved dKH out and it's raising in the tank so hopefully (keeping my fingers crossed) things will be back to normal soon.

Have a Happy Holiday if we don't talk before then!

Grumpy

GB do you have any plating monti's?? They suck up alk like crazy. Try doing a kalk drip for couple weeks also that will raise your alk alot. I use that several times a week and have a reactor and the alk stays about 9

I did read from the beginning but may have misunderstood it.

Glad to see you got it back on track though

Curious as everyone else what the build up consisted of though. I'm assuming this hasn't happened before in the reactor.

If it was to happen again (hopefully not), would you be willing to conduct a little test? Or even mail me some of the residue.

I'm curious what the chemical makeup/levels of the "buildup" will be when dissolved.

Originally Posted by Grumpy Bass

What I have concluded is that when the reactor media is low (~1/3 full) and having the pH set too low (6.2'ish), there is a build of at the base of the reactor that somehow (still don't understand exactly why) inhibits the release of Alk but not Calcium or Magnesium, this is the only thing I can figure out what happened.

Just wanted to comment on this first.

If the PH in the reactor is low enough to break down the media releasing Alk and Mg then it has to be releasing Ca. You cant liberate just Alk from calcium carbonate or just Alk and Mg. Breaking down calcium carbonate substrate is the opposite of calcification and will release Ca, Alk and Mg in a 16ppm to 16ppm to 1ppm ratio. Thats just how it works and you cant get around it using an acidic seawater solution like in a Ca reactor.


My thoughts are that the change in salt mix is whats caused this. The new salt may have a higher Ca content and or lower Alk content and its moved the ratio of the saltwater away from what your used to seeing.

To correct this you need to add something like baking soda to bring the Alk up where you want it or do water changes with water thats mixed to the ratio you want. You can make all the adjustments to the Ca reactor you want but that will never correct the imbalance between Ca,Mg and Alk because the reactor will only add them in the 16-16-1 ratio.

As always... thanks for you feedback.

Originally Posted by chris&barb

Just wanted to comment on this first.

If the PH in the reactor is low enough to break down the media releasing Alk and Mg then it has to be releasing Ca. (Yes, this is my understanding the process too. Please note there is no problem with Ca or Mg, the levels were very high, this post is about very low Alk only) You cant liberate just Alk from calcium carbonate or just Alk and Mg. Breaking down calcium carbonate substrate is the opposite of calcification and will release Ca, Alk and Mg in a 16ppm to 16ppm to 1ppm ratio (Thank you, its good to know the expected ratios). Thats just how it works and you cant get around it using an acidic seawater solution like in a Ca reactor.


My thoughts are that the change in salt mix is whats caused this. The new salt may have a higher Ca content and or lower Alk content and its moved the ratio of the saltwater away from what your used to seeing. I would like to think it were simple like the salt but I can't find any correlation in testing the salt alone vrs the system water (I posted the tank and salt values earlier).. but never say never right.

To correct this you need to add something like baking soda to bring the Alk up where you want it or do water changes with water thats mixed to the ratio you want. You can make all the adjustments to the Ca reactor you want but that will never correct the imbalance between Ca,Mg and Alk because the reactor will only add them in the 16-16-1 ratio.

I really prefer not to add something like sodium bicarbonate without first trying understand what changed, especially so quickly. I understanding adding sodium bicarbonate will raise the Alk.. I found a calibration protocol to ensure proper additions had I needed to go there but I didnt need to...Phew.

Replacing the reactor media corrected my problem but what is still completely unclear to me... A) Why it happend so quickly B) why only suppression of Alk and not Ca or Mg, using the 16:16:1 ratio it does not make sense to me... I'm still missing something.

I'm keeping a close eye on everything in case I see a change again.


Thanks everyone, really appreciated!

Grumpy